feat: drag-and-drop reorder for daily focus items

Add HTML5 drag-and-drop within domain groups on the focus page.
Items can be dragged to reorder within their domain; cross-domain
drag is prevented. Uses hidden form POST (no fetch/XHR). Arrow
buttons kept as fallback.

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

routers/focus.py

@@ -222,6 +222,20 @@ async def reorder_focus(
     return RedirectResponse(url=f"/focus?focus_date={focus_date}", status_code=303)
 
 
+@router.post("/reorder-all")
+async def reorder_all_focus(
+    request: Request,
+    item_ids: str = Form(...),
+    focus_date: str = Form(...),
+    db: AsyncSession = Depends(get_db),
+):
+    repo = BaseRepository("daily_focus", db)
+    ids = [i.strip() for i in item_ids.split(",") if i.strip()]
+    if ids:
+        await repo.reorder(ids)
+    return RedirectResponse(url=f"/focus?focus_date={focus_date}", status_code=303)
+
+
 @router.post("/{focus_id}/toggle")
 async def toggle_focus(focus_id: str, request: Request, db: AsyncSession = Depends(get_db)):
     repo = BaseRepository("daily_focus", db)