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/data.js

@@ -1,3 +1,4 @@
+import { migrateScriptKeys } from './episode-script-keys.js'
 import { mkdir, readFile, readdir, stat, unlink, writeFile } from 'node:fs/promises'
 import path from 'node:path'
 import { randomUUID } from 'node:crypto'
@@ -804,7 +805,11 @@ export async function loadEpisodeScriptsFromDisk() {
   try {
     const raw = await readFile(EPISODE_SCRIPTS_FILE, 'utf8')
     const parsed = JSON.parse(raw)
-    state.episodeScripts = (parsed && typeof parsed === 'object' && !Array.isArray(parsed)) ? parsed : {}
+    const loaded = (parsed && typeof parsed === 'object' && !Array.isArray(parsed)) ? parsed : {}
+    const { scripts, changed } = migrateScriptKeys(loaded)
+    state.episodeScripts = scripts
+    // Persist the move to season-episode keys once, so it isn't redone on every start
+    if (changed) queueEpisodeScriptsWrite()
   } catch {
     state.episodeScripts = {}
   }