fix(session): repair corrupt legacy-stem files in list_sessions

list_sessions() silently dropped corrupt session files whose filename
stem was a legacy non-base64 name (e.g. telegram_12345.jsonl from the
old lossy path scheme). The repair path called _repair(fallback_key),
but _repair re-encodes the key via _storage_key(), producing a
different base64 filename that never matches the actual file on disk.

Add an optional path parameter to _repair so callers can pass the
actual file path directly, bypassing the key-to-filename round trip.

Signed-off-by: axelray-dev <110029405+axelray-dev@users.noreply.github.com>

nanobot/session/manager.py

@@ -539,9 +539,10 @@ class SessionManager:
                 logger.info("Recovered session {} from corrupt file ({} messages)", key, len(repaired.messages))
             return repaired
 
-    def _repair(self, key: str) -> Session | None:
+    def _repair(self, key: str, *, path: Path | None = None) -> Session | None:
         """Attempt to recover a session from a corrupt JSONL file."""
-        path = self._get_session_path(key)
+        if path is None:
+            path = self._get_session_path(key)
         if not path.exists():
             return None
 
@@ -893,7 +894,7 @@ class SessionManager:
                                 }
                             )
             except Exception:
-                repaired = self._repair(fallback_key)
+                repaired = self._repair(fallback_key, path=path)
                 if repaired is not None:
                     sessions.append(
                         {