Implement prototype: venue-driven simulation core, scenarios, tests, and playable entrance scene

- Godot 4.3 project scaffold with first-person guard, procedural world,
  interaction HUD, access inspection, radio forms, debug overlay, shift review
- Simulation core: ShiftCoordinator, VenueScenario, EventScheduler, NPCController/FSM,
  AccessVerifier, EscalationManager, RadioSystem, IncidentRecorder,
  ReputationEvaluator, CrowdSystem, EventBus
- Three authored scenarios (Hollywood Blvd building, The Joke Shop, TV studio)
- Custom headless test runner (25 tests) replacing editor-dependent GUT,
  plus GitHub Actions CI
- Documentation workflow live: README, PLAN (tech stack), TODO/DONE, MEMORY

src/autoload/save.gd

@@ -0,0 +1,39 @@
+extends Node
+## Autoload for local persistence (JSON in user://). Wrapped in an autoload so UI
+## nodes never touch the filesystem directly.
+
+const SHIFT_RESULTS_FILE := "shift_results.json"
+const SETTINGS_FILE := "settings.json"
+
+func _load_json(file_name: String) -> Variant:
+	var path := "user://" + file_name
+	if not FileAccess.file_exists(path):
+		return null
+	var text := FileAccess.get_file_as_string(path)
+	if text.is_empty():
+		return null
+	var parsed = JSON.parse_string(text)
+	return parsed
+
+func _save_json(file_name: String, data: Variant) -> Error:
+	var path := "user://" + file_name
+	var text := JSON.stringify(data, "\t")
+	var f := FileAccess.open(path, FileAccess.WRITE)
+	if f == null:
+		return FileAccess.get_open_error()
+	f.store_string(text)
+	f.close()
+	return OK
+
+## Load previous shift results. Returns Array of Dictionaries or [].
+func load_shift_results() -> Array:
+	var data = _load_json(SHIFT_RESULTS_FILE)
+	if data is Array:
+		return data
+	return []
+
+## Append one shift result and save. Returns Error.
+func save_shift_result(result: Dictionary) -> Error:
+	var results := load_shift_results()
+	results.append(result)
+	return _save_json(SHIFT_RESULTS_FILE, results)