Add multi-project support: projects entity, picker home page, project context

Projects become the top-level container; SOPs and Work Packages belong to one.

Backend:
- New projects table + CRUD (/api/projects).
- sops.project_id (FK, cascade) and work_packages.project_id added;
  list/latest/metrics endpoints accept a project_id filter.

Front end (now under html/):
- project-data.js: shared API-first ProjectData adapter with localStorage
  fallback + active-project helpers.
- Home page: removed "About This Suite"; added a Project picker (create /
  use sample / select). Tool cards stay hidden until a project is active and
  carry &project=<id>; hero shows the active project.
- Suite reads ?project, resolves it, shows it in the header, and prefills the
  SOP project fields; passes &project into the WP-creator iframe.
- WP creator stamps projectId onto saved packages.

SOP/WP localStorage is not yet namespaced per project (next step).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

html/wp-creation-index.html

@@ -276,6 +276,7 @@
 </aside>
 
 <script src="feedback-config.js"></script>
+<script src="project-data.js"></script>
 <script src="wp-creation-app.js"></script>
 </body>
 </html>