Phase 17/18 closure: stockpile filter UI + day summary + atmospheric audio

Three-agent fan-out (gdscript-refactor x3) closing deferred polish:

- Stockpile chip filter UI: new StockpilePanel (layer 18, right-anchored,
  mirrors WorkbenchPanel). 5-priority segmented control + 21-chip 4-col
  filter grid using Item.ALL_TYPES; wildcard (empty accepted_types) shows
  all chips checked with 'All' hint, first explicit pick switches to
  explicit-list mode. Selection chain extended to pawn → workbench →
  stockpile with mutual exclusion. 12 ui.stockpile.* + 13 item.* keys.

- DaySummaryCard: layer-19 modal auto-opens at dusk→night via day_ended,
  auto-pauses sim, shows day+season header, weather row, stats grid with
  green/yellow/red tension bar, Continue dismiss + backdrop tap.
  Settings 'Show end-of-day summary' toggle persists via GameState.

- Atmospheric audio: rain ambient loop (Cozy Melodies Pack 6) on
  weather_changed rain/storm with 0.5s fade-out on clear; thunder sting
  (Magic and Spells 6) on rain→storm transition; raid warning sting
  (Sword Pack 1, 'blades drawn') on EventBus.wolf_spawned. All on SFX
  bus — inherits existing slider + suspend mute.

Contracts pre-written before fan-out: EventBus.stockpile_selected /
stockpile_deselected / wolf_spawned signals; WolfSpawner._trigger_raid
+ _on_request_wolf_spawn now emit wolf_spawned with the spawned array.

MCP runtime verified: StockpilePanel opens with 21 chips, DaySummaryCard
renders weather row + tension bar + auto-pause, rain_player.playing=true
on weather_changed(rain), all three new SFX keys in Audio.SFX_FILES.

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

autoload/event_bus.gd

@@ -57,9 +57,12 @@ signal pawn_selected(pawn)                         ## Emitted when Selection pic
 signal pawn_deselected                             ## Emitted when Selection clears — closes PawnDetailPanel.
 signal workbench_selected(workbench)
 signal workbench_deselected
+signal stockpile_selected(zone)                    ## Emitted when Selection picks a StockpileZone — opens StockpilePanel for filter editing.
+signal stockpile_deselected                        ## Emitted when Selection clears the active stockpile.
 signal pawn_priority_changed(pawn, category: StringName, level: int) ## Emitted when priority matrix updates a cell.
 signal alert_added(severity: StringName, text: String, focus_tile: Vector2i) ## Emitted by gameplay subsystems to surface a player notice. severity = info | warn | danger.
 signal request_wolf_spawn(count: int)              ## Phase 15 EventCatalog → WolfSpawner. Decouples threat-event effects from spawner.
+signal wolf_spawned(wolves: Array)                 ## Emitted by WolfSpawner AFTER a raid wave has been instantiated; carries the spawned Wolf nodes. Audio uses this for raid-warning sting.
 signal day_ended(summary: Dictionary)              ## Emitted by Clock at dusk→night boundary; carries the end-of-day recap dict.
 
 # Phase 18 — Alert wiring (dangling signals surfaced to AlertsLog).