Fix: stale cleanup in processors must fail loudly on permission errors

Phase 5c-2 failed because shutil.rmtree(ignore_errors=True) silently
failed to clean up root-owned legacy files in processing/{hash}/,
letting the processor proceed into a half-cleaned directory and then
crash on subsequent file writes.

Changes: removed ignore_errors=True, wrapped in try/except that logs
and re-raises, so the processor fails early and visibly if stale
cleanup fails.

Recovery from Phase 5c-2 failure.

lib/processors/transcript_processor.py

@@ -57,8 +57,18 @@ def pre_flight(content_path, meta_path, db, config):
     )
     proc_dir = os.path.join(processing_root, file_hash)
     concepts_dir = os.path.join(config['paths']['concepts'], file_hash)
-    shutil.rmtree(proc_dir, ignore_errors=True)
-    shutil.rmtree(concepts_dir, ignore_errors=True)
+    if os.path.exists(proc_dir):
+        try:
+            shutil.rmtree(proc_dir)
+        except Exception as e:
+            logger.error("Stale cleanup failed for %s: %s", proc_dir, e)
+            raise
+    if os.path.exists(concepts_dir):
+        try:
+            shutil.rmtree(concepts_dir)
+        except Exception as e:
+            logger.error("Stale cleanup failed for %s: %s", concepts_dir, e)
+            raise
 
     # Hash dedupe: if hash exists in catalogue, delete the pair and return
     conn = db._get_conn()