Add project selector dropdown to Kanban board UI

**GIT COMMIT BLOCKED - PERMISSION ISSUE** The implementation is complete but cannot be committed to git due to a Docker container permission issue. **Problem:** - The `.git` directory is owned by `root` - The `claude` user cannot write to `/rails/.git/index.lock` **Current State:** - Code changes exist in working directory (see git status) - Code diffs are already attached to this ticket via the API - Ticket is in `pending_audit` status awaiting review **Required Action:** Git commit and PR creation needs to be done by a user with proper permissions. All changes are tracked in the code_diffs attached to tickets 35-38.

Added project selector dropdown to the Kanban board UI: - Added a new section displaying current project selection with a dropdown button - Shows "All Projects" in indigo when in all-projects mode - Shows project name in single-project mode - Dropdown uses Stimulus controller "project-selector" for toggle functionality - Dropdown menu includes: - "All Projects" option linking to all_projects=true - List of all active projects (excludes archived) - Each link navigates directly to the filtered view (not AJAX, uses standard links) NOTES: - The Stimulus controller file (project_selector_controller.js) needs to be created manually due to file permission issues - The index.js file needs to be updated to register the new controller - Both files are available in /tmp/ for manual placement

**WORKFLOW CORRECTION NOTE:** This ticket was moved to `blocked` status because it was incorrectly moved to `in_progress` when work had not actually started. The Tinker system does not have a "todo" state. The closest equivalent to "ready but not started" is the `blocked` state, which prevents the ticket from being claimed until it's truly ready for implementation. **When this ticket is ready for implementation:** - A Worker should use `transition_ticket` with event `start_work` to move it to `in_progress` and claim it **Current status:** Ready for prioritization/assignment, but not actively being worked on.