Pete Adventure News: emit seam, !news command, cold-start backfill

gogobee's game-side of Pete's push-based Adventure news feed. Emits
structured event *facts* (not prose) to Pete's ingest endpoint over a
durable queue; Pete owns voice/authoring/publishing.

- internal/peteclient: durable pete_emit_queue + retry sender; Fact
  payload; FEATURE_PETE_NEWS master switch.
- pete.go: emitFact enforces runtime kill-switch + per-player opt-out
  (anonymize, never drop); zone-clear + realm-first tiering; !news
  command (player optout/optin, admin on/off).
- bootstrap_pete_news.go: cold-start backfill replays deaths +
  single-holder achievements + zone realm-firsts, backdated + NoPush,
  idempotent, fires only once the seam is live; seeds news_realm_firsts.
- Emit sites: death, zone_first, rival_result, milestone, arrival.
- db.go: pete_emit_queue, news_optout (+opted_out_at), news_realm_firsts.

Unshipped. Deploy Pete first, then set FEATURE_PETE_NEWS + ingest env.

Claude-Session: https://claude.ai/code/session_017mEwUmmS7aQTP2NQXj6rUa

internal/plugin/dnd_combat.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"gogobee/internal/db"
+	"gogobee/internal/peteclient"
 	"maunium.net/go/mautrix/id"
 )
 
@@ -575,4 +576,30 @@ func markAdventureDead(userID id.UserID, source, location string) {
 	if err := saveAdvCharacter(char); err != nil {
 		slog.Error("dnd: kill on combat loss", "user", userID, "err", err)
 	}
+	emitDeathNews(userID, location)
+}
+
+// emitDeathNews files a PRIORITY death dispatch to Pete's adventure news. No-op
+// unless the seam is enabled. Uses the character name (never the Matrix handle);
+// skips silently if the name is unknown.
+func emitDeathNews(userID id.UserID, location string) {
+	name := charName(userID)
+	if name == "" {
+		return
+	}
+	lvl := 0
+	if dc, _ := LoadDnDCharacter(userID); dc != nil {
+		lvl = dc.Level
+	}
+	ts := nowUnix()
+	emitFact(peteclient.Fact{
+		GUID:       fmt.Sprintf("death:%s:%d", userHash(userID), ts),
+		EventType:  "death",
+		Tier:       "priority",
+		Subject:    name,
+		Zone:       location,
+		Level:      lvl,
+		Outcome:    "lost",
+		OccurredAt: ts,
+	}, userID, "")
 }