feat(backup)!: exact --images-* matching and --hard-restart-projects

Match --images-no-stop-required and --images-no-backup-required against
the container's exact .Config.Image instead of a substring, so callers
pass full repo:tag references (registry prefix included) and near-miss
image names no longer flip the stop/skip decision. Rename the opt-in
--hard-compose-restart flag to --hard-restart-projects.

The e2e suite pins a SPOT for the DB images and in-container data dirs
(postgres:alpine at /var/lib/postgresql, mariadb:latest at
/var/lib/mysql) and passes exact image refs to the --images-* flags.

BREAKING CHANGE: --images-* now require exact image references, not
substrings; --hard-compose-restart is renamed to --hard-restart-projects.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/e2e/test_e2e_dump_only_sql_mixed_run.py

@@ -1,6 +1,8 @@
 import unittest
 
 from .helpers import (
+    POSTGRES_IMAGE,
+    POSTGRES_DATA_DIR,
     backup_path,
     cleanup_docker,
     create_minimal_compose_dir,
@@ -70,8 +72,8 @@ class TestE2EDumpOnlySqlMixedRun(unittest.TestCase):
                 "-e",
                 f"POSTGRES_PASSWORD={cls.pg_password}",
                 "-v",
-                f"{cls.db_volume}:/var/lib/postgresql/data",
-                "postgres:16-alpine",
+                f"{cls.db_volume}:{POSTGRES_DATA_DIR}",
+                POSTGRES_IMAGE,
             ]
         )
         wait_for_postgres(cls.pg_container, user="postgres", timeout_s=90)
@@ -122,10 +124,7 @@ class TestE2EDumpOnlySqlMixedRun(unittest.TestCase):
             "--database-containers",
             cls.pg_container,
             "--images-no-stop-required",
-            "alpine",
-            "postgres",
-            "mariadb",
-            "mysql",
+            POSTGRES_IMAGE,
             "--dump-only-sql",
             "--backups-dir",
             cls.backups_dir,