fix(daemon): consume the MovieCommand channel

Nothing drained AppState's movie_commands mpsc, so manual search and
one-click grab were accepted with 202 and then did nothing until the
64-slot buffer filled and the endpoint started 503ing.

A new daemon task drains it: Search resets the movie's backoff and
runs the targeted-search + grab lane immediately; Grab sends the
already-chosen release straight to Transmission.

Closes #107

.sqlx/query-e6274f081ce0751331e78f7fec573e088d08e3683fc60e84ff325e95fe42d803.json

@@ -0,0 +1,12 @@
+{
+  "db_name": "SQLite",
+  "query": "UPDATE movies SET search_attempts = 0, last_searched_at = NULL,\n                updated_at = strftime('%Y-%m-%dT%H:%M:%fZ', 'now')\n         WHERE id = ?",
+  "describe": {
+    "columns": [],
+    "parameters": {
+      "Right": 1
+    },
+    "nullable": []
+  },
+  "hash": "e6274f081ce0751331e78f7fec573e088d08e3683fc60e84ff325e95fe42d803"
+}