Add body-camera timeline to the shift review

- New src/game/ui/event_timeline.gd flattens every recorded incident event
  (ADR-0005) into one time-ordered list and shows time, person, and a one-line
  summary. Step with Left/Right or the buttons; Esc returns to the review. No live
  3D replay in this first version.
- Shift review gains a "Body camera timeline" button that hands the review to the
  timeline; the review dim is hidden while it is open (stacked overlays made the
  screen nearly black) and restored on close.
- ShiftCoordinator records started_at_ms so the review can stamp events as mm:ss.
- 8 new string keys for the timeline UI and the review button.

Tests/docs
- Headless suite 113 -> 120 (test_event_timeline.gd), new smoke_timeline.gd that
  opens the timeline from the review, steps through every event, and closes back.
- README, TODO section moved to DONE, MEMORY notes. Version 0.2.6.

src/core/shift_coordinator.gd

@@ -21,6 +21,8 @@ signal phase_changed(phase: int)
 var scenario: VenueScenario = null
 var duration_s: float = 900.0
 var elapsed_s: float = 0.0
+## Wall-clock start, so the shift review can show event times as mm:ss.
+var started_at_ms: int = 0
 var current_phase: int = Rules.Phase.EARLY
 var running := false
 
@@ -65,6 +67,7 @@ func start() -> void:
 		return
 	running = true
 	_shift_finished = false
+	started_at_ms = Time.get_ticks_msec()
 	elapsed_s = 0.0
 	_spawn_accum_s = 0.0
 	current_phase = _phase_for_time(0.0)
@@ -137,6 +140,7 @@ func build_review() -> Dictionary:
 		"scenario_id": scenario.id if scenario else "",
 		"duration_s": duration_s,
 		"elapsed_s": elapsed_s,
+		"started_at_ms": started_at_ms,
 		"phase_at_end": current_phase,
 		"spawned_count": spawned_count,
 		"incidents": recorder.to_dict(),