feat: flatten output into variants/ and intermediates/

Drop per-job subdirs for phone-friendly Syncthing layout with
stem-suffixed filenames; keep web state in meta/.

Co-authored-by: Cursor <cursoragent@cursor.com>

NOTES.md

@@ -11,7 +11,8 @@
 
 - SFTPGo removed; drop path is Syncthing
 - Data share: `/home/frank/sync.schwenk.online/data/livef12`
-  (`incoming/` + `jobs/` + `processed.json`)
+  (`incoming/` + `variants/` + `intermediates/` + `meta/` + `processed.json`)
+- Flat phone-friendly names: `{stem}_original.jpg`, `{stem}_v1.png`, …
 - Old path `/home/frank/live.f12.rocks/data` no longer used by compose
   (migration/cleanup manual)
 - Host port 12121 can be closed after cutover