Add season field to episode scripts and improve global search; v2.0.50

Tag scripts with a season number (with an RSS-feed backfill for
existing uploads), surface it in search results, and fix word-boundary
matching plus a title/script-match dedup bug in the search merge logic.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

package.json

@@ -1,7 +1,7 @@
 {
   "name": "siteforge",
   "private": true,
-  "version": "2.0.49",
+  "version": "2.0.50",
   "type": "module",
   "scripts": {
     "dev": "vite",