fix(projects): tab counter NaN when a status bucket is empty

services/projects.py:get_project_summary built task_counts dynamically
from a GROUP BY query, so a project with no done tasks would omit the
'done' key entirely. Frontend's TypeScript interface declares all three
lifecycle keys as required, and ProjectView.vue summed them to render
the Tasks tab counter — undefined + N = NaN.

Two fixes:
1. Backend: initialise task_counts with {todo: 0, in_progress: 0,
   done: 0} so the service returns the contract its consumers expect.
   Catches the same problem for HomeView's project widget and any
   other consumer.
2. Frontend: defensive ?? 0 on the tab-counter sum, so the existing
   deploy renders correctly even before the backend rolls.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/fabledassistant/services/projects.py

@@ -199,7 +199,10 @@ async def get_project_summary(user_id: int, project_id: int) -> dict:
             )
             .group_by(Note.status)
         )
-        task_counts: dict[str, int] = {}
+        # Initialise all three lifecycle keys to 0 so consumers can sum them
+        # safely without `?? 0` guards. Frontend interface declares all three
+        # as required; rendering `undefined + N` yields NaN.
+        task_counts: dict[str, int] = {"todo": 0, "in_progress": 0, "done": 0}
         for status, count in task_rows.fetchall():
             task_counts[status] = count