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/tests/test_migrations.py

@@ -16,6 +16,7 @@ constraints, SERIAL sequences) that can't be expressed on `Base.metadata`, so co
 noise; they're filtered out. The column/table signal is the "someone changed a model without a migration"
 case worth failing on.
 """
+
 from alembic import command
 from alembic.autogenerate import compare_metadata
 from alembic.config import Config
@@ -26,7 +27,12 @@ from app.db import Base, engine
 # The diff ops that mean a real table/column disagreement (presence AND shape) — not the index/
 # constraint/sequence noise from migration-only objects.
 _DRIFT_OPS = {
-    "add_table", "remove_table", "add_column", "remove_column", "modify_type", "modify_nullable",
+    "add_table",
+    "remove_table",
+    "add_column",
+    "remove_column",
+    "modify_type",
+    "modify_nullable",
 }
 
 
@@ -39,7 +45,7 @@ def _structural_drift():
         diffs = compare_metadata(ctx, Base.metadata)
     drift = []
     for d in diffs:
-        for entry in (d if isinstance(d, list) else [d]):
+        for entry in d if isinstance(d, list) else [d]:
             if isinstance(entry, tuple) and entry and entry[0] in _DRIFT_OPS:
                 drift.append(entry)
     return drift