Implement TODO backlog: LATE phase fix, protester, CALL_SOMEONE, door lock, flashlight, persistence, navmesh, JSON localization, and release tooling

- Fix LATE shift phase (start 700s) so the violent-threat event is reachable
- Add PROTESTER archetype (rules, profile, colors, events in public venues)
- Add CALL_SOMEONE reaction (FSM -> ARGUING, influencer/trespasser/protester weights)
- Door lock: DoorState core class, L binding, red/green visual indicator,
  locked doors thwart FORCE_ENTRY
- Flashlight: G binding, SpotLight3D, perception radius bonus at evening/late
- Persistence: save shift results via Save autoload, history + best score on
  review screen, round-trip test
- Navigation: flat NavigationRegion3D navmesh, NavigationAgent3D path following
  with direct-movement fallback; steps made visual-only so NPCs reach entrance
- Localization: strings moved to content/strings.en.json (loader keeps
  lookup/fmt signatures; coverage test over all keys)
- Distribution: export_presets.cfg (Linux/Windows/macOS), tools/build_releases.sh,
  docs/RELEASING.md, prominent README Downloads section
- Remove stale signal_bus.gd (invalid static-signal experiment)
- Tests: 53 passing across 9 suites

src/test/tests/test_strings.gd

@@ -14,6 +14,15 @@ func test_strings_format() -> bool:
 	var b := TestUtils.check_eq(Strings.fmt("react.comply", ["Tourist"]), "Tourist complies and steps back.", "reaction formats")
 	return a and b
 
+func test_strings_json_backed_all_resolve() -> bool:
+	## Every key in the JSON-loaded table must resolve to a value other than
+	## the key itself (fail-safe would otherwise mask broken entries).
+	for key in Strings.TABLE.keys():
+		var value: String = Strings.lookup(key)
+		if value == key:
+			return TestUtils.fail("key %s resolves to itself — table entry missing" % key)
+	return true
+
 func test_strings_cover_ui_keys() -> bool:
 	## Every key referenced by the HUD and game manager must exist.
 	var required := [