docs: add project documentation and improve robustness

- Add ARCHITECTURE.md, FAQ.md, LLM.md documentation
- Add LICENSE (MIT), CODE_OF_CONDUCT.md, PR template
- Add .editorconfig for consistent formatting
- Add check.sh script for validation
- Fix ESLint errors in hud-config.ts and settings-reader.ts
- Various test and component improvements

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,19 @@
+## Summary
+
+Describe the change and its intent.
+
+## Testing
+
+- [ ] `bun run lint` (tui)
+- [ ] `bun run typecheck` (tui)
+- [ ] `bun test` (tui)
+
+## Screenshots / TUI Capture
+
+If this changes the HUD UI, include a screenshot or recording.
+
+## Checklist
+
+- [ ] Updated docs or help text if needed
+- [ ] Added/updated tests for new behavior
+- [ ] No new lint or type errors