feat: checkbox batch trip delete on the Pi (local-only)

- Pi history page gets a select checkbox column + 'Delete selected' button
  (mirrors the server UI)
- POST /api/trips/delete batch endpoint
- app_sql.delete_trips_batch() + deleted_trip_markers table so a later trip
  rebuild can't resurrect locally-deleted trips
- Deletion is local-only: raw tracking rows are kept and the remote server
  is never notified (it keeps its archival copy recomputed from uploaded rows)

modules/app_sql.py

@@ -116,6 +116,14 @@ SQL_CREATE_ALERT_STATE_TABLE = """CREATE TABLE IF NOT EXISTS alert_state (
                                 LAST_VALUE text
                             );"""
 
+# Local-only trip deletion markers. trip_id == the trip's START_TRACKING_ID, so
+# a later rebuild can skip re-inserting a trip the user deleted. This is
+# independent of the server's own deleted_trip_markers — Pi deletions are never
+# pushed to the remote server (archival copy kept there).
+SQL_CREATE_DELETED_TRIP_MARKERS_TABLE = """CREATE TABLE IF NOT EXISTS deleted_trip_markers (
+                                trip_id integer PRIMARY KEY
+                            );"""
+
 
 def create_conn(db_file):
     """Open a SQLite connection to db_file, creating its parent folder if needed.
@@ -161,6 +169,7 @@ def get_conn():
             create_table(_conn, SQL_CREATE_TRIPS_TABLE)
             create_table(_conn, SQL_CREATE_TRIP_BUILD_STATE_TABLE)
             create_table(_conn, SQL_CREATE_ALERT_STATE_TABLE)
+            create_table(_conn, SQL_CREATE_DELETED_TRIP_MARKERS_TABLE)
             _migrate_tracking_table(_conn)
             _migrate_trips_table(_conn)
             _migrate_trip_build_state_table(_conn)
@@ -435,6 +444,12 @@ def refresh_trips(force=False):
     trips = app_trip.build_trip_summaries(rows)
     with _conn_lock:
         try:
+            deleted_ids = {
+                row[0] for row in conn.execute(
+                    "SELECT trip_id FROM deleted_trip_markers"
+                ).fetchall()
+            }
+            trips = [t for t in trips if t["id"] not in deleted_ids]
             conn.execute(
                 "DELETE FROM trips WHERE END_TRACKING_ID >= ?",
                 (rebuild_start_id,),
@@ -604,16 +619,36 @@ def get_trip_route(trip_id, max_points=2000):
 
 
 def delete_trip(trip_id):
-    """Delete a computed trip record. Raw tracking rows are NOT removed."""
+    """Delete a computed trip record. Raw tracking rows are NOT removed, and the
+    deletion is local-only — the remote server keeps its own archival copy
+    (recomputed from the uploaded tracking rows) and is never told about this.
+
+    The trip id is remembered in deleted_trip_markers so a later trip rebuild
+    can't silently resurrect it."""
     conn = get_conn()
     if conn is None:
         return False
     with _conn_lock:
         cur = conn.execute("DELETE FROM trips WHERE id = ?", (trip_id,))
+        if cur.rowcount > 0:
+            conn.execute(
+                "INSERT OR IGNORE INTO deleted_trip_markers (trip_id) VALUES (?)",
+                (trip_id,),
+            )
         conn.commit()
         return cur.rowcount > 0
 
 
+def delete_trips_batch(trip_ids):
+    """Delete multiple computed trips locally (raw tracking rows preserved,
+    remote server untouched). Returns the number deleted."""
+    deleted = 0
+    for trip_id in trip_ids:
+        if delete_trip(trip_id):
+            deleted += 1
+    return deleted
+
+
 def get_setting(key, default=None):
     """Read a persisted UI/app setting (e.g. the dashcam-upload toggle)."""
     conn = get_conn()