Add version system, tax tracking, lottery winner DMs, fmtEuro, audit fixes

- Version system: per-plugin versions via Versioned interface, crash_log and
  version_history DB tables, !version command, crash stats in !botinfo
- Tax tracking: tax_ledger table, trackTaxPaid across all communityTax and
  communityPotAdd sites, tax paid display in !stats and !superstatsexplusalpha
- Lottery: DM winners with winning ticket details and matched numbers bolded
- fmtEuro: generic currency formatter with thousand separators across all
  economy display paths
- Audit fixes: streak_decayed column for Streak Survivor achievement,
  combat_narrative empty-phase guard, crafting success rate integer division,
  RecordCrash nil-DB guard

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

internal/plugin/plugin.go

@@ -13,6 +13,7 @@ import (
 
 	"gogobee/internal/db"
 	"gogobee/internal/util"
+	"gogobee/internal/version"
 
 	"maunium.net/go/mautrix"
 	"maunium.net/go/mautrix/event"
@@ -57,6 +58,19 @@ type Plugin interface {
 	Init() error
 }
 
+// Versioned is an optional interface plugins can implement to declare their version.
+type Versioned interface {
+	Version() string
+}
+
+// PluginVersion returns the version for a plugin, or "1.0.0" if it doesn't implement Versioned.
+func PluginVersion(p Plugin) string {
+	if v, ok := p.(Versioned); ok {
+		return v.Version()
+	}
+	return "1.0.0"
+}
+
 // dmCache maps user IDs to their DM room IDs to avoid creating duplicate rooms.
 var (
 	dmCache   = make(map[id.UserID]id.RoomID)
@@ -764,6 +778,7 @@ func safeGo(label string, fn func()) {
 		defer func() {
 			if r := recover(); r != nil {
 				slog.Error("goroutine panic recovered", "label", label, "panic", r)
+				db.RecordCrash(version.Short(), label, fmt.Sprintf("%v", r))
 			}
 		}()
 		fn()