build(lint): gate make test on a clean ruff run

ruff was never wired into this repository: no target, no CI step, no pin.
It reported 45 findings across sources and tests, so nothing enforced
what the codebase already mostly followed.

Adds `make ruff` (check + format --check), `make ruff-fix`, and `make
lint` as its alias, and makes `make test` run lint as a fourth parallel
spur. The CI workflow calls `make test`, so it is covered there too. The
linter is pinned in a `lint` extra: a ruff minor bump changes which rules
fire, and with the suite gating on a clean run an unpinned linter would
fail it on an unrelated day.

The 45 findings are fixed rather than configured away. Three needed a
decision instead of the mechanical fix:

- The generation timestamp keeps its local wall clock (DTZ005 waived).
  Generations sort by that name, and UTC would order new ones before the
  existing ones wherever the offset is positive - "newest generation" is
  what every restore path selects on.
- The per-volume `copy` closure now binds volume_name and vol_dir as
  default arguments (B023). It only worked because it is called inside
  the same iteration.
- The two CLI top-level handlers keep their blind except (BLE001
  waived): turning any failure into exit 1 is what a CLI boundary is
  for. The two in run.py did not need it and were narrowed to what they
  actually catch.

Also drops the comments that restate the code: the section banners in
restore/__main__.py, the filename repeated as line 1 of nine test files,
step narration above the statement it narrates, and a block in app.py
documenting parameters that had moved to another module. What names a
trip-wire stays - the snapshot destination rule, the mysql-binary
absence in MariaDB 11 images, the session-scoped FOREIGN_KEY_CHECKS, the
spooled temp file for multi-GB dumps, and the negative control that
loses its discriminating power if it ever passes.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/e2e/test_e2e_mariadb_full.py

@@ -1,21 +1,20 @@
-# tests/e2e/test_e2e_mariadb_full.py
 import unittest
 
 from .helpers import (
-    MARIADB_IMAGE,
     MARIADB_DATA_DIR,
-    backup_run,
+    MARIADB_IMAGE,
     backup_path,
+    backup_run,
     cleanup_docker,
     create_minimal_compose_dir,
     ensure_empty_dir,
     latest_version_dir,
     require_docker,
-    unique,
-    write_databases_csv,
     run,
+    unique,
     wait_for_mariadb,
     wait_for_mariadb_sql,
+    write_databases_csv,
 )
 
 
@@ -71,7 +70,6 @@ class TestE2EMariaDBFull(unittest.TestCase):
             cls.db_container, user=cls.db_user, password=cls.db_password, timeout_s=90
         )
 
-        # Create table + data via the dedicated user (TCP)
         run(
             [
                 "docker",
@@ -79,9 +77,11 @@ class TestE2EMariaDBFull(unittest.TestCase):
                 cls.db_container,
                 "sh",
                 "-lc",
-                f"mariadb -h 127.0.0.1 -u{cls.db_user} -p{cls.db_password} "
-                f'-e "CREATE TABLE {cls.db_name}.t (id INT PRIMARY KEY, v VARCHAR(50)); '
-                f"INSERT INTO {cls.db_name}.t VALUES (1,'ok');\"",
+                (
+                    f"mariadb -h 127.0.0.1 -u{cls.db_user} -p{cls.db_password} "
+                    f'-e "CREATE TABLE {cls.db_name}.t (id INT PRIMARY KEY, v VARCHAR(50)); '
+                    f"INSERT INTO {cls.db_name}.t VALUES (1,'ok');\""
+                ),
             ]
         )
 
@@ -112,8 +112,10 @@ class TestE2EMariaDBFull(unittest.TestCase):
                 cls.db_container,
                 "sh",
                 "-lc",
-                f"mariadb -h 127.0.0.1 -u{cls.db_user} -p{cls.db_password} "
-                f'-e "DROP TABLE {cls.db_name}.t;"',
+                (
+                    f"mariadb -h 127.0.0.1 -u{cls.db_user} -p{cls.db_password} "
+                    f'-e "DROP TABLE {cls.db_name}.t;"'
+                ),
             ]
         )
 
@@ -161,8 +163,10 @@ class TestE2EMariaDBFull(unittest.TestCase):
                 self.db_container,
                 "sh",
                 "-lc",
-                f"mariadb -h 127.0.0.1 -u{self.db_user} -p{self.db_password} "
-                f'-N -e "SELECT v FROM {self.db_name}.t WHERE id=1;"',
+                (
+                    f"mariadb -h 127.0.0.1 -u{self.db_user} -p{self.db_password} "
+                    f'-N -e "SELECT v FROM {self.db_name}.t WHERE id=1;"'
+                ),
             ]
         )
         self.assertEqual((p.stdout or "").strip(), "ok")