docs: add project docs, GitHub DX, fire-tools stamp

- CLAUDE.md with commands, structure, key constraints
- .claude/rules/ coding standards + workflows
- docs/architecture.md with design decisions
- .github/ CI workflow, issue templates, PR template
- LICENSE (MIT)
- .fire-tools.json initialization stamp
- README.md rewritten with features, quick start, stack table

.claude/rules/workflows.md

@@ -0,0 +1,50 @@
+---
+description: Recurring task patterns — read when fixing issues, adding features, or running tests
+---
+
+# Workflows
+
+## Add a Feature
+
+1. Read `docs/architecture.md` to understand where new code belongs
+2. Write the test first (failing)
+3. Implement minimum code to pass
+4. `pnpm test` — full suite
+5. `pnpm lint:fix` — Biome
+6. Commit: `feat: <description>`
+
+## Fix a Bug
+
+1. Grep codebase for identifiers mentioned in the bug report
+2. Read the 2–3 most relevant files
+3. Write a failing test that reproduces the problem
+4. Implement the minimal fix
+5. `pnpm vitest run <path/to/test.ts>` — verify test passes
+6. `pnpm lint:fix` — pass lint
+7. Commit: `fix: <description>`
+
+## Regenerate API Types
+
+Run after updating `openapi.json`:
+
+```bash
+pnpm generate:api
+# → overwrites src/api/schema.d.ts
+# Do not edit schema.d.ts manually
+```
+
+## Run Targeted Tests
+
+```bash
+pnpm vitest run src/path/to/file.test.ts
+pnpm vitest run --testNamePattern="<substring>"
+pnpm vitest src/path/to/file.test.ts  # watch mode
+```
+
+## Add a New Route
+
+1. Create `src/routes/<flat-route-name>.tsx` using TanStack Router flat-route syntax
+2. Export `const Route = createFileRoute("/<path>")({ component: Foo })`
+3. Vite plugin auto-regenerates `src/routeTree.gen.ts` on save
+4. Add nav link to `src/components/layout/Sidebar.tsx` if top-level
+5. Cast all `navigate()` / `<Link>` params as `as never`