Episode scripts: file by season + episode so numbers can repeat per book; search labels for current series; v2.9.6

- Scripts keyed "<season>-<episode>" (legacy ones migrate on first start; unseasoned ones keep their plain key)
- Season backfill handles episode numbers shared across seasons (title match fallback)
- Fix: "Backfill seasons from RSS" was swallowed by the upload route
- Global search labels script results with the title of the series playing now (both lanes), not just finished books

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

server/state.js

@@ -54,7 +54,7 @@ export const state = {
   studyCertificates: [],
   studyCertificatesWritePromise: Promise.resolve(),
 
-  // episodeScripts: { [episodeNumber]: { text, title, filename, season, uploadedAt } }
+  // episodeScripts: { ["<season>-<episode>" or "<episode>" if no season]: { episodeNumber, text, title, filename, season, uploadedAt } }
   episodeScripts: {},
   episodeScriptsWritePromise: Promise.resolve(),