fix(security): address CodeQL clear-text logging and weak hashing alerts

- Convert f-string log interpolation to %s-style formatting in
  app/api/pipelines.py and app/api/saved_searches.py to prevent
  clear-text logging of request-derived data (CodeQL: clear-text
  logging of sensitive information)
- Replace plain hashlib.sha256() with PBKDF2-HMAC-SHA256 via
  hash_token() in app/auth.py for Bearer token verification,
  consistent with how tokens are stored in api_tokens.py (CodeQL:
  use of weak cryptographic hashing on sensitive data)
- Remove redundant {exc} from logger.exception() calls (the
  traceback is already captured by logger.exception())
- Update test to verify PBKDF2 hash instead of plain SHA-256

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

app/api/api_tokens.py

@@ -6,8 +6,8 @@ uploads, scripted integrations).
 
 Tokens use ``secrets.token_urlsafe`` from the Python standard library
 (no extra dependencies) and are prefixed with ``de_`` for easy
-identification.  Only a SHA-256 hash is persisted; the plaintext is
-returned exactly once at creation time.
+identification.  Only a PBKDF2-HMAC-SHA256 hash is persisted; the
+plaintext is returned exactly once at creation time.
 """
 
 import hashlib

app/api/pipelines.py

@@ -291,15 +291,15 @@ def create_pipeline(request: Request, db: DbSession, body: PipelineCreate) -> di
         db.add(pipeline)
         db.commit()
         db.refresh(pipeline)
-    except Exception as exc:
+    except Exception:
         db.rollback()
-        logger.exception(f"Failed to create pipeline user={user_id}: {exc}")
+        logger.exception("Failed to create pipeline user=%s", user_id)
         raise HTTPException(
             status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
             detail="Failed to create pipeline",
         )
 
-    logger.info(f"Pipeline created: id={pipeline.id}, owner={user_id}, name={name!r}")
+    logger.info("Pipeline created: id=%s, owner=%s, name=%r", pipeline.id, user_id, name)
     return _serialize_pipeline(pipeline)
 
 
@@ -387,15 +387,15 @@ def update_pipeline(pipeline_id: int, request: Request, db: DbSession, body: Pip
     try:
         db.commit()
         db.refresh(pipeline)
-    except Exception as exc:
+    except Exception:
         db.rollback()
-        logger.exception(f"Failed to update pipeline id={pipeline_id}: {exc}")
+        logger.exception("Failed to update pipeline id=%s", pipeline_id)
         raise HTTPException(
             status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
             detail="Failed to update pipeline",
         )
 
-    logger.info(f"Pipeline updated: id={pipeline_id}, user={user_id}")
+    logger.info("Pipeline updated: id=%s, user=%s", pipeline_id, user_id)
     return _serialize_pipeline(pipeline, include_steps=True, db=db)
 
 
@@ -425,15 +425,15 @@ def delete_pipeline(pipeline_id: int, request: Request, db: DbSession) -> None:
         db.query(PipelineStep).filter(PipelineStep.pipeline_id == pipeline_id).delete()
         db.delete(pipeline)
         db.commit()
-    except Exception as exc:
+    except Exception:
         db.rollback()
-        logger.exception(f"Failed to delete pipeline id={pipeline_id}: {exc}")
+        logger.exception("Failed to delete pipeline id=%s", pipeline_id)
         raise HTTPException(
             status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
             detail="Failed to delete pipeline",
         )
 
-    logger.info(f"Pipeline deleted: id={pipeline_id}, user={user_id}")
+    logger.info("Pipeline deleted: id=%s, user=%s", pipeline_id, user_id)
 
 
 # ---------------------------------------------------------------------------

app/api/saved_searches.py

@@ -190,15 +190,15 @@ def create_saved_search(
         db.add(saved_search)
         db.commit()
         db.refresh(saved_search)
-    except Exception as exc:
+    except Exception:
         db.rollback()
-        logger.exception(f"Failed to create saved search for user={user_id}: {exc}")
+        logger.exception("Failed to create saved search for user=%s", user_id)
         raise HTTPException(
             status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
             detail="Failed to save search",
         )
 
-    logger.info(f"Saved search created: user={user_id}, name={name!r}")
+    logger.info("Saved search created: user=%s, name=%r", user_id, name)
     return _serialize_saved_search(saved_search)
 
 
@@ -263,15 +263,15 @@ def update_saved_search(
     try:
         db.commit()
         db.refresh(saved_search)
-    except Exception as exc:
+    except Exception:
         db.rollback()
-        logger.exception(f"Failed to update saved search id={search_id}, user={user_id}: {exc}")
+        logger.exception("Failed to update saved search id=%s, user=%s", search_id, user_id)
         raise HTTPException(
             status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
             detail="Failed to update saved search",
         )
 
-    logger.info(f"Saved search updated: id={search_id}, user={user_id}")
+    logger.info("Saved search updated: id=%s, user=%s", search_id, user_id)
     return _serialize_saved_search(saved_search)
 
 
@@ -294,12 +294,12 @@ def delete_saved_search(search_id: int, request: Request, db: DbSession):
     try:
         db.delete(saved_search)
         db.commit()
-    except Exception as exc:
+    except Exception:
         db.rollback()
-        logger.exception(f"Failed to delete saved search id={search_id}, user={user_id}: {exc}")
+        logger.exception("Failed to delete saved search id=%s, user=%s", search_id, user_id)
         raise HTTPException(
             status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
             detail="Failed to delete saved search",
         )
 
-    logger.info(f"Saved search deleted: id={search_id}, user={user_id}")
+    logger.info("Saved search deleted: id=%s, user=%s", search_id, user_id)