fix(credentials): improve exception handling in key_storage.py (#6153)

Replace bare except Exception: clauses with specific exception handling:

- delete_aden_api_key(): Catch FileNotFoundError, PermissionError at debug
  level; log unexpected errors at WARNING with exc_info=True
- _read_credential_key_file(): Catch FileNotFoundError, PermissionError at
  debug level; log unexpected errors at WARNING with exc_info=True
- _read_aden_from_encrypted_store(): Catch FileNotFoundError, PermissionError,
  KeyError at debug level; log unexpected errors at WARNING with exc_info=True

This makes credential issues easier to diagnose by:
- Logging unexpected errors at WARNING level (visible in production)
- Including full stack traces with exc_info=True
- Keeping expected failures (file not found, permissions) at debug level

Fixes #5931

core/framework/credentials/key_storage.py

@@ -149,8 +149,14 @@ def delete_aden_api_key() -> None:
 
         storage = EncryptedFileStorage()
         storage.delete(ADEN_CREDENTIAL_ID)
+    except (FileNotFoundError, PermissionError) as e:
+        logger.debug("Could not delete %s from encrypted store: %s", ADEN_CREDENTIAL_ID, e)
     except Exception:
-        logger.debug("Could not delete %s from encrypted store", ADEN_CREDENTIAL_ID)
+        logger.warning(
+            "Unexpected error deleting %s from encrypted store",
+            ADEN_CREDENTIAL_ID,
+            exc_info=True,
+        )
 
     os.environ.pop(ADEN_ENV_VAR, None)
 
@@ -167,8 +173,10 @@ def _read_credential_key_file() -> str | None:
             value = CREDENTIAL_KEY_PATH.read_text(encoding="utf-8").strip()
             if value:
                 return value
+    except (FileNotFoundError, PermissionError) as e:
+        logger.debug("Could not read %s: %s", CREDENTIAL_KEY_PATH, e)
     except Exception:
-        logger.debug("Could not read %s", CREDENTIAL_KEY_PATH)
+        logger.warning("Unexpected error reading %s", CREDENTIAL_KEY_PATH, exc_info=True)
     return None
 
 
@@ -196,6 +204,12 @@ def _read_aden_from_encrypted_store() -> str | None:
         cred = storage.load(ADEN_CREDENTIAL_ID)
         if cred:
             return cred.get_key("api_key")
+    except (FileNotFoundError, PermissionError, KeyError) as e:
+        logger.debug("Could not load %s from encrypted store: %s", ADEN_CREDENTIAL_ID, e)
     except Exception:
-        logger.debug("Could not load %s from encrypted store", ADEN_CREDENTIAL_ID)
+        logger.warning(
+            "Unexpected error loading %s from encrypted store",
+            ADEN_CREDENTIAL_ID,
+            exc_info=True,
+        )
     return None