Add forex plugin, stability fixes, and async HTTP dispatch

- Add forex plugin (Frankfurter v2 API) with rate lookups, analysis,
  DM-based alerts, and daily cron poll. Backfills 1 year of history
  on startup for moving averages and buy signal scoring.

- Fix bot hang caused by SQLite lock contention in reminder polling:
  rows cursor was held open while writing to the same DB. Collect
  results first, close cursor, then process. Same fix in milkcarton.

- Add sync retry loop so the bot reconnects after network drops
  instead of silently exiting. StopSync() for clean Ctrl+C shutdown.

- Add panic recovery to all dispatch, syncer, and cron paths.

- Make all HTTP-calling plugin commands async (goroutines) so a slow
  or dead external API cannot block the message dispatch pipeline.
  Affects: lookup, stocks, forex, anime, movies, concerts, gaming,
  retro, wotd, urls, howami.

- Extract DisplayName to Base, add db.Exec helper, convert silent
  error discards across the codebase.

- Fix UNO mercy-kill bug (eliminated bot continues playing), adventure
  DM nag spam, stats column mismatch, per-call regex/replacer allocs.

- Update README: forex commands, Finance section, 47 plugins.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/plugin/forex.go

@@ -0,0 +1,262 @@
+package plugin
+
+import (
+	"fmt"
+	"log/slog"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"maunium.net/go/mautrix"
+	"maunium.net/go/mautrix/id"
+)
+
+// ForexPlugin tracks USD exchange rates against EUR and JPY using the
+// Frankfurter API (ECB-sourced, no API key required). Stores daily history,
+// computes buy signals, and provides rate alerts.
+type ForexPlugin struct {
+	Base
+	httpClient *http.Client
+}
+
+func NewForexPlugin(client *mautrix.Client) *ForexPlugin {
+	return &ForexPlugin{
+		Base: NewBase(client),
+		httpClient: &http.Client{
+			Timeout: 30 * time.Second,
+		},
+	}
+}
+
+func (p *ForexPlugin) Name() string { return "forex" }
+
+func (p *ForexPlugin) Commands() []CommandDef {
+	return []CommandDef{
+		{Name: "fx", Description: "Forex rates and analysis", Usage: "!fx rate [EUR|JPY] · !fx report [EUR|JPY] · !fx setalert <cur> <rate> · !fx alerts · !fx delalert <cur> <rate>", Category: "Entertainment"},
+	}
+}
+
+func (p *ForexPlugin) Init() error {
+	go p.backfill()
+	return nil
+}
+
+func (p *ForexPlugin) OnReaction(_ ReactionContext) error { return nil }
+
+func (p *ForexPlugin) OnMessage(ctx MessageContext) error {
+	if !p.IsCommand(ctx.Body, "fx") {
+		return nil
+	}
+
+	args := strings.TrimSpace(p.GetArgs(ctx.Body, "fx"))
+	if args == "" {
+		return p.SendReply(ctx.RoomID, ctx.EventID,
+			"Usage: `!fx rate [EUR|JPY]` · `!fx report [EUR|JPY]` · `!fx setalert <currency> <rate>` · `!fx alerts` · `!fx delalert <currency> <rate>`")
+	}
+
+	parts := strings.Fields(args)
+	sub := strings.ToLower(parts[0])
+
+	// DB-only and instant subcommands
+	switch sub {
+	case "setalert":
+		return p.cmdSetAlert(ctx, parts[1:])
+	case "alerts":
+		return p.cmdListAlerts(ctx)
+	case "delalert":
+		return p.cmdDelAlert(ctx, parts[1:])
+	case "help":
+		return p.SendReply(ctx.RoomID, ctx.EventID, fxHelpText)
+	}
+
+	// API-calling subcommands run async
+	switch sub {
+	case "rate", "report":
+		go func() {
+			var err error
+			if sub == "rate" {
+				err = p.cmdRate(ctx, parts[1:])
+			} else {
+				err = p.cmdReport(ctx, parts[1:])
+			}
+			if err != nil {
+				slog.Error("forex: handler error", "err", err)
+			}
+		}()
+		return nil
+	default:
+		return p.SendReply(ctx.RoomID, ctx.EventID, fmt.Sprintf("Unknown subcommand `%s`. Try `!fx help`.", parts[0]))
+	}
+}
+
+const fxHelpText = "**Forex Commands**\n\n" +
+	"`!fx rate [EUR|JPY]` — current rate + quick signal\n" +
+	"`!fx report [EUR|JPY]` — full analysis (averages, 52w range, buy score)\n" +
+	"`!fx setalert <currency> <rate>` — alert when USD/currency reaches threshold\n" +
+	"`!fx alerts` — list active alerts in this room\n" +
+	"`!fx delalert <currency> <rate>` — remove an alert\n" +
+	"`!fx help` — this message"
+
+// ── Command Handlers ────────────────────────────────────────────────────────
+
+func (p *ForexPlugin) cmdRate(ctx MessageContext, args []string) error {
+	currencies := fxParseCurrencies(args)
+	rates, err := p.fxLiveRates(currencies)
+	if err != nil {
+		return p.SendReply(ctx.RoomID, ctx.EventID, fmt.Sprintf("Could not fetch rates: %v", err))
+	}
+
+	var lines []string
+	for _, cur := range currencies {
+		rate, ok := rates[cur]
+		if !ok {
+			continue
+		}
+		sig, err := p.fxComputeSignal(cur, rate)
+		if err != nil {
+			lines = append(lines, fmt.Sprintf("%s %s: %s (insufficient data for analysis)", fxMeta[cur].Emoji, cur, fxFormatRate(cur, rate)))
+			continue
+		}
+		lines = append(lines, sig.FormatQuick())
+	}
+	return p.SendReply(ctx.RoomID, ctx.EventID, strings.Join(lines, "\n"))
+}
+
+func (p *ForexPlugin) cmdReport(ctx MessageContext, args []string) error {
+	currencies := fxParseCurrencies(args)
+	rates, err := p.fxLiveRates(currencies)
+	if err != nil {
+		return p.SendReply(ctx.RoomID, ctx.EventID, fmt.Sprintf("Could not fetch rates: %v", err))
+	}
+
+	var sections []string
+	for _, cur := range currencies {
+		rate, ok := rates[cur]
+		if !ok {
+			continue
+		}
+		sig, err := p.fxComputeSignal(cur, rate)
+		if err != nil {
+			sections = append(sections, fmt.Sprintf("%s **%s** — %s\n_Insufficient history for full analysis._", fxMeta[cur].Emoji, cur, fxFormatRate(cur, rate)))
+			continue
+		}
+		sections = append(sections, sig.FormatReport())
+	}
+	return p.SendReply(ctx.RoomID, ctx.EventID, strings.Join(sections, "\n\n---\n\n"))
+}
+
+func (p *ForexPlugin) cmdSetAlert(ctx MessageContext, args []string) error {
+	if len(args) < 2 {
+		return p.SendReply(ctx.RoomID, ctx.EventID, "Usage: `!fx setalert <currency> <rate>` — e.g. `!fx setalert JPY 155`")
+	}
+	cur := strings.ToUpper(args[0])
+	if !fxIsTracked(cur) {
+		return p.SendReply(ctx.RoomID, ctx.EventID, fmt.Sprintf("Unknown currency `%s`. Tracked: %s", cur, strings.Join(fxTrackedCurrencies, ", ")))
+	}
+	threshold, err := strconv.ParseFloat(args[1], 64)
+	if err != nil || threshold <= 0 {
+		return p.SendReply(ctx.RoomID, ctx.EventID, fmt.Sprintf("Invalid rate `%s`.", args[1]))
+	}
+	if err := fxSaveAlert(string(ctx.Sender), cur, threshold); err != nil {
+		return p.SendReply(ctx.RoomID, ctx.EventID, fmt.Sprintf("Could not save alert: %v", err))
+	}
+	meta := fxMeta[cur]
+	return p.SendReply(ctx.RoomID, ctx.EventID,
+		fmt.Sprintf("Alert set: I'll notify when 1 USD >= **%s %s** %s", fxFormatRate(cur, threshold), cur, meta.Emoji))
+}
+
+func (p *ForexPlugin) cmdListAlerts(ctx MessageContext) error {
+	alerts, err := fxAlertsForUser(string(ctx.Sender))
+	if err != nil {
+		return p.SendReply(ctx.RoomID, ctx.EventID, fmt.Sprintf("Error: %v", err))
+	}
+	if len(alerts) == 0 {
+		return p.SendReply(ctx.RoomID, ctx.EventID, "No active alerts. Set one with `!fx setalert <currency> <rate>`.")
+	}
+	var sb strings.Builder
+	sb.WriteString("**Your FX alerts:**\n")
+	for _, a := range alerts {
+		meta := fxMeta[a.Currency]
+		status := ""
+		if a.FiredAt != 0 {
+			status = fmt.Sprintf(" _(fired %s)_", time.Unix(a.FiredAt, 0).UTC().Format("Jan 2 15:04 UTC"))
+		}
+		sb.WriteString(fmt.Sprintf("  %s `%s %s`%s\n",
+			meta.Emoji, fxFormatRate(a.Currency, a.Threshold), a.Currency, status))
+	}
+	sb.WriteString("\nAlerts are delivered via DM.")
+	return p.SendReply(ctx.RoomID, ctx.EventID, sb.String())
+}
+
+func (p *ForexPlugin) cmdDelAlert(ctx MessageContext, args []string) error {
+	if len(args) < 2 {
+		return p.SendReply(ctx.RoomID, ctx.EventID, "Usage: `!fx delalert <currency> <rate>` — e.g. `!fx delalert JPY 155`")
+	}
+	cur := strings.ToUpper(args[0])
+	threshold, err := strconv.ParseFloat(args[1], 64)
+	if err != nil {
+		return p.SendReply(ctx.RoomID, ctx.EventID, fmt.Sprintf("Invalid rate `%s`.", args[1]))
+	}
+	if err := fxDeleteAlert(string(ctx.Sender), cur, threshold); err != nil {
+		return p.SendReply(ctx.RoomID, ctx.EventID, fmt.Sprintf("Error: %v", err))
+	}
+	return p.SendReply(ctx.RoomID, ctx.EventID, fmt.Sprintf("Alert for `%s %s` removed.", fxFormatRate(cur, threshold), cur))
+}
+
+// ── Daily Poll (called by cron) ─────────────────────────────────────────────
+
+func (p *ForexPlugin) DailyPoll() {
+	rates, err := p.fxFetchCurrent(fxTrackedCurrencies)
+	if err != nil {
+		slog.Error("forex: daily poll fetch failed", "err", err)
+		return
+	}
+
+	today := time.Now().UTC().Format("2006-01-02")
+	for cur, rate := range rates {
+		fxSaveRate(cur, today, rate)
+	}
+
+	fxResetExpiredAlerts()
+	p.checkAlerts(rates)
+}
+
+func (p *ForexPlugin) checkAlerts(rates map[string]float64) {
+	alerts, err := fxAllAlerts()
+	if err != nil {
+		slog.Error("forex: alert check error", "err", err)
+		return
+	}
+	for _, a := range alerts {
+		if a.FiredAt != 0 {
+			continue
+		}
+		rate, ok := rates[a.Currency]
+		if !ok || rate < a.Threshold {
+			continue
+		}
+		meta := fxMeta[a.Currency]
+		msg := fmt.Sprintf("**FX Alert** %s — 1 USD = **%s %s** has reached your threshold of **%s**.",
+			meta.Emoji, fxFormatRate(a.Currency, rate), a.Currency,
+			fxFormatRate(a.Currency, a.Threshold))
+		p.SendDM(id.UserID(a.UserID), msg)
+		fxMarkAlertFired(a)
+	}
+}
+
+// ── Helpers ─────────────────────────────────────────────────────────────────
+
+func fxParseCurrencies(args []string) []string {
+	var out []string
+	for _, a := range args {
+		c := strings.ToUpper(a)
+		if fxIsTracked(c) {
+			out = append(out, c)
+		}
+	}
+	if len(out) == 0 {
+		return fxTrackedCurrencies
+	}
+	return out
+}