style: apply ruff format across backend + scripts (line-length 100)

Mechanical, whole-tree `ruff format` pass — no behaviour change. Recorded in
.git-blame-ignore-revs (next commit) so git blame skips it.

backend/app/security.py

@@ -28,6 +28,7 @@ def verify_password(password: str, hashed: str | None) -> bool:
         # Any failure (mismatch, malformed hash) is a non-match — never raise to the caller.
         return False
 
+
 _fernet: Fernet | None = (
     Fernet(settings.token_encryption_key.encode()) if settings.token_encryption_key else None
 )