Add drag & drop reordering of trips on the dashboard

- trip_members.sort_order (per-user, migrated) drives GET /api/trips order
- PATCH /api/trips/:id/order updates only the caller's membership row
- Trip cards get a drag handle reusing the generalized row-reorder helper;
  clicking the card still navigates

src/server/db.js

@@ -23,6 +23,7 @@ CREATE TABLE IF NOT EXISTS trip_members (
   trip_id INTEGER NOT NULL REFERENCES trips(id),
   user_id INTEGER NOT NULL REFERENCES users(id),
   role TEXT NOT NULL DEFAULT 'editor',
+  sort_order INTEGER NOT NULL DEFAULT 0,
   PRIMARY KEY (trip_id, user_id)
 );
 
@@ -72,6 +73,7 @@ const MIGRATIONS = [
   { table: 'entries', column: 'rental', ddl: 'ALTER TABLE entries ADD COLUMN rental TEXT' },
   { table: 'entries', column: 'end_date', ddl: 'ALTER TABLE entries ADD COLUMN end_date TEXT' },
   { table: 'entries', column: 'transport_mode', ddl: 'ALTER TABLE entries ADD COLUMN transport_mode TEXT' },
+  { table: 'trip_members', column: 'sort_order', ddl: 'ALTER TABLE trip_members ADD COLUMN sort_order INTEGER NOT NULL DEFAULT 0' },
 ];
 
 function applyMigrations(db) {

src/server/routes/trips.js

@@ -116,13 +116,16 @@ export default function tripsRoutes(db) {
   const router = express.Router();
 
   const listForUser = db.prepare(`
-    SELECT t.id, t.name, t.start_date, t.end_date, t.owner_id, t.currency, tm.role,
+    SELECT t.id, t.name, t.start_date, t.end_date, t.owner_id, t.currency, tm.role, tm.sort_order,
       (SELECT COUNT(*) FROM trip_members WHERE trip_id = t.id) AS member_count,
       (SELECT COUNT(*) FROM entries WHERE trip_id = t.id) AS entry_count
     FROM trips t
     JOIN trip_members tm ON tm.trip_id = t.id AND tm.user_id = ?
-    ORDER BY t.created_at DESC, t.id DESC
+    ORDER BY tm.sort_order, t.created_at DESC, t.id DESC
   `);
+  const updateMemberOrder = db.prepare(
+    'UPDATE trip_members SET sort_order = ? WHERE trip_id = ? AND user_id = ?'
+  );
   const insertTrip = db.prepare(
     'INSERT INTO trips (name, start_date, end_date, owner_id, currency, join_code) VALUES (?, ?, ?, ?, ?, ?)'
   );
@@ -233,6 +236,18 @@ export default function tripsRoutes(db) {
     res.status(200).json({ trip: tripJson(getTrip.get(ctx.tripId)) });
   });
 
+  // PATCH /api/trips/:id/order  { sort_order }  — caller's own dashboard order.
+  router.patch('/:id/order', (req, res) => {
+    const ctx = requireMember(req, res);
+    if (!ctx) return;
+    const { sort_order } = req.body || {};
+    if (!Number.isInteger(sort_order)) {
+      return res.status(400).json({ error: 'sort_order must be an integer' });
+    }
+    updateMemberOrder.run(sort_order, ctx.tripId, req.session.userId);
+    res.status(200).json({ sort_order });
+  });
+
   // DELETE /api/trips/:id  (owner only)
   router.delete('/:id', (req, res) => {
     const ctx = requireMember(req, res);