refactor: rename project to LedGrab, split HA integration into separate repo

- Rename Python package: wled_controller -> ledgrab
- Rename env var prefix: WLED_ -> LEDGRAB_ (with auto-migration for old vars)
- Rename localStorage key: wled_api_key -> ledgrab_api_key (with migration)
- Rename HA integration domain: wled_screen_controller -> ledgrab
- Update all imports, build scripts, Docker, installer, config, docs
- Remove HA integration (moved to ledgrab-haos-integration repo)
- Remove hacs.json (belongs in HA repo now)
- Add startup warning for users with old WLED_ env vars
- All tests pass (715/715), ruff clean, tsc clean, frontend builds

TODO-release.md

@@ -5,7 +5,7 @@
 - [ ] Rename all references to "WLED" in user-facing strings, class names, module names, config keys, file paths, and documentation
 - [ ] The app is **LedGrab** — not tied to WLED specifically. WLED is just one of many supported output protocols
 - [ ] Audit: i18n keys, page titles, tray labels, installer text, pyproject.toml description, README, CLAUDE.md, context files, API docs
-- [ ] Rename `wled_controller` package → decide on new package name (e.g. `ledgrab`)
+- [ ] Rename `ledgrab` package → decide on new package name (e.g. `ledgrab`)
 - [ ] Update import paths, entry points, config references, build scripts, Docker, CI/CD
 - [ ] **Migration required** if renaming storage paths or config keys (see data migration policy in CLAUDE.md)