Free hunt: only spawn ghosts that have an uploaded video

Add `AND webm_path IS NOT NULL` to the /api/freehunt pool so free-hunt
mode only selects ghosts with real media (and their derived webp/image
fallbacks), never bare procedural-wisp ghosts.

routes/api.js

@@ -75,7 +75,9 @@ router.get('/scan/:code', (req, res) => {
 router.get('/freehunt', (req, res) => {
   const n = Math.min(parseInt(req.query.n, 10) || 3, 10);
   const type = req.query.type; // optional red|yellow|blue filter
-  let q = 'SELECT * FROM ghosts WHERE enabled = 1 AND is_boss = 0';
+  // Free hunt only spawns ghosts with an uploaded video (webm); the webp/image
+  // fallbacks are derived from it, so these always render on every platform.
+  let q = 'SELECT * FROM ghosts WHERE enabled = 1 AND is_boss = 0 AND webm_path IS NOT NULL';
   const params = [];
   if (type && ['red', 'yellow', 'blue'].includes(type)) {
     q += ' AND type = ?';