Add project CRUD API (GET/POST/PATCH/DELETE) with ownership checks and
transactional delete. Add diagram list filtering by projectId and
unorganized query params with typed Zod query schema for Hono RPC
type safety. Create DiagramSidebar with Projects tree (expand/collapse,
inline rename) and Recent tab. Add project picker to CreateDiagramDialog.
Includes 15 schema validation tests (107 total passing).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add diagram/project DB schema, CRUD API, dashboard pages with grid/card/
empty state, create dialog with type selector, editor placeholder, and
26 schema validation tests. Includes code review fixes: soft-delete
filter on GET /:id, error handling, keyboard accessibility, type-safe
API response types, and error states on pages.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>