Prepare first downloadable release: install export templates, build 0.1.0 binaries, add publish helper

- Install Godot 4.3 export templates locally and fix macOS export
  (enable rendering/textures/vram_compression/import_etc2_astc)
- Build Linux/Windows/macOS artifacts into build/ via tools/build_releases.sh;
  Linux binary passes headless smoke test
- Add tools/publish_release.sh (creates Gitea release + uploads assets with a token)
- TODO: mark build/install steps done; publishing v0.1.0 + link verification
  remain as the single action blocker (needs GITEA_TOKEN)

MEMORY.md

@@ -26,7 +26,7 @@ Session memory for durable decisions, state, and gotchas. Keep concise, remove o
 - Run tests: `godot --headless --path . --script res://src/test/test_runner.gd`
 - Boot check: `godot --headless --path . --quit-after 120`
 - Screenshot tool: `godot --path . --script res://src/test/take_screenshot.gd` (writes to `user://screenshot.png`).
-- Release build: `./tools/build_releases.sh` requires export templates (see `docs/RELEASING.md`).
+- Release build verified locally: export templates for 4.3 installed at `~/.local/share/godot/export_templates/4.3.stable/`; `./tools/build_releases.sh` produced Linux/Windows/macOS artifacts for 0.1.0 in `build/` and the Linux binary passed a headless smoke test. Publishing to Gitea still needs a token (see `tools/publish_release.sh`, `docs/RELEASING.md`).
 
 ## Known Issues / Notes
 
@@ -34,7 +34,7 @@ Session memory for durable decisions, state, and gotchas. Keep concise, remove o
 - Headless (dummy renderer) logs "Parameter m is null" from `mesh_get_surface_count`; it does not occur with a real GL driver and does not affect logic.
 - Steps are visual-only (no collider) so NPCs can path to the entrance; the guard spawns on the landing so it never needs to climb.
 - Persistence tests write into the real `user://shift_results.json` (harmless local pollution of the demo history).
-- Export presets and release scripts are **not yet verified with real export templates** (none installed on this machine); see `docs/RELEASING.md` before first release.
+- macOS export required `rendering/textures/vram_compression/import_etc2_astc=true` in `project.godot` (universal build demands ETC2 ASTC enabled).
 - Joke Shop `door_staff_lines` authored but not yet surfaced in the prototype UI (tracked in TODO).
 
 ## Open Questions