drop multi-node ssh execution, unify job runner to local + fix job completion atomicity

- remove nodes table, ssh service, nodes api, NodesPage route
- execute.ts: local-only spawn, atomic CAS job claim via UPDATE status
- wrap job done + subtitle_files insert + review_plans status in db transaction
- stream ffmpeg output per line with 500ms throttled flush
- bump version to 2026.04.13

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "netfelix-audio-fix",
-	"version": "2026.03.27",
+	"version": "2026.04.13",
 	"scripts": {
 		"dev:server": "NODE_ENV=development bun --hot server/index.tsx",
 		"dev:client": "vite",