feat: Add project deletion; untrack CLAUDE.md from git

- Add DELETE /project/<id>/delete route with ownership check, active-run
  guard, filesystem cleanup (shutil.rmtree), and StoryState cascade delete
- Add delete button + confirmation modal to project page header
- Add delete button + per-project confirmation modal to dashboard cards
- Add CLAUDE.md to .gitignore and remove it from git tracking

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

templates/project.html

@@ -11,6 +11,11 @@
             <button class="btn btn-sm btn-outline-info ms-2" data-bs-toggle="modal" data-bs-target="#cloneProjectModal" title="Clone/Fork Project" data-bs-toggle="tooltip">
                 <i class="fas fa-code-branch"></i>
             </button>
+            {% if not locked %}
+            <button class="btn btn-sm btn-outline-danger ms-2" data-bs-toggle="modal" data-bs-target="#deleteProjectModal" title="Delete Project">
+                <i class="fas fa-trash"></i>
+            </button>
+            {% endif %}
         </div>
         <div class="mt-2">
             <span class="badge bg-secondary">{{ bible.project_metadata.genre }}</span>
@@ -546,6 +551,26 @@
     </div>
 </div>
 
+<!-- Delete Project Modal -->
+<div class="modal fade" id="deleteProjectModal" tabindex="-1">
+    <div class="modal-dialog">
+        <form class="modal-content" action="/project/{{ project.id }}/delete" method="POST">
+            <div class="modal-header bg-danger text-white">
+                <h5 class="modal-title"><i class="fas fa-exclamation-triangle me-2"></i>Delete Project</h5>
+                <button type="button" class="btn-close btn-close-white" data-bs-dismiss="modal"></button>
+            </div>
+            <div class="modal-body">
+                <p>This will permanently delete <strong>{{ project.name }}</strong> and all its runs, files, and generated books.</p>
+                <p class="text-danger fw-bold">This action cannot be undone.</p>
+            </div>
+            <div class="modal-footer">
+                <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Cancel</button>
+                <button type="submit" class="btn btn-danger">Delete Project</button>
+            </div>
+        </form>
+    </div>
+</div>
+
 <!-- Full Bible JSON Modal -->
 <div class="modal fade" id="fullBibleModal" tabindex="-1">
     <div class="modal-dialog modal-lg modal-dialog-scrollable">