Branching zones G6: dependent surfaces re-keyed on graph nodes

- Harvest tables (expedition + standalone) now keyed by node_id; legacy
  room-idx entries auto-migrate via read-fallback + drop-on-save.
- Narration salts swapped from run.CurrentRoom to narrationCadence(run)
  (= len(visited_nodes)-1) so flavor pickers survive G9 column drop.
- !zone map renders the graph (BFS by PosX/PosY) when the gate is on:
  ✓/▶/· status, ╳ for locked-only edges, secrets hidden until visited.
- Region-boundary hook in graph advance/!zone go updates expedition
  CurrentRegion + visited list when from/to nodes differ — without
  burning supplies or retiring runs (the graph IS the run state).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/plugin/dnd_zone_combat.go

@@ -299,7 +299,7 @@ func (p *AdventurePlugin) applyTrapEffectWithDetect(
 		// failed detection no longer contradicts the next line. The mismatch
 		// where "Perception roll pays off" preceded a tripped trap was
 		// caused by this line firing unconditionally.
-		if line := twinBeeLine(zone.ID, DMTrapDetected, run.RunID, run.CurrentRoom); line != "" {
+		if line := twinBeeLine(zone.ID, DMTrapDetected, run.RunID, narrationCadence(run)); line != "" {
 			b.WriteString(line)
 			b.WriteString("\n")
 		}