feat(update): snapshot pairing data before git pull (#16383)

Quick state snapshot now includes pairing JSONs (generic + legacy +
Feishu comment pairing), and `hermes update` takes a pre-update
snapshot labeled `pre-update` before pulling.

Pairing data lives outside state.db in platform-specific JSONs under
~/.hermes/pairing/, ~/.hermes/platforms/pairing/, and
~/.hermes/feishu_comment_pairing.json.  The update command already
couldn't touch $HERMES_HOME, but #15733 reports lost pairing after
an update — this gives users something to restore from via
`/snapshot list` / `/snapshot restore <id>` if anything clobbers
the approved-user lists.

- Extend _QUICK_STATE_FILES with pairing paths (files + dirs)
- Snapshot walks directories recursively and records each file in the
  manifest individually so restore logic is unchanged
- _cmd_update_impl calls create_quick_snapshot(label='pre-update')
  after 'Found N new commits' and before 'Pulling updates'
- Snapshot failures are logged at debug and never block the update

Refs #15733.

tests/hermes_cli/test_backup.py

@@ -1141,3 +1141,80 @@ class TestQuickSnapshot:
         deleted = prune_quick_snapshots(keep=3, hermes_home=hermes_home)
         assert deleted == 7
         assert len(list_quick_snapshots(hermes_home=hermes_home)) == 3
+
+    def test_snapshot_includes_pairing_directories(self, hermes_home):
+        """Pairing JSONs live outside state.db — snapshot must capture them
+        recursively (generic + per-platform) so approved-user lists survive
+        disasters like #15733."""
+        from hermes_cli.backup import create_quick_snapshot
+
+        # Generic pairing store (new location)
+        (hermes_home / "platforms" / "pairing").mkdir(parents=True)
+        (hermes_home / "platforms" / "pairing" / "telegram-approved.json").write_text(
+            '{"12345": {"user_name": "alice"}}'
+        )
+        (hermes_home / "platforms" / "pairing" / "discord-approved.json").write_text(
+            '{"67890": {"user_name": "bob"}}'
+        )
+        # Legacy pairing store (old location)
+        (hermes_home / "pairing").mkdir()
+        (hermes_home / "pairing" / "matrix-approved.json").write_text(
+            '{"@charlie:server": {"user_name": "charlie"}}'
+        )
+        # Feishu's separate JSON
+        (hermes_home / "feishu_comment_pairing.json").write_text(
+            '{"doc_abc": {"allow_from": ["user_xyz"]}}'
+        )
+
+        snap_id = create_quick_snapshot(hermes_home=hermes_home)
+        assert snap_id is not None
+
+        snap_dir = hermes_home / "state-snapshots" / snap_id
+        assert (snap_dir / "platforms" / "pairing" / "telegram-approved.json").exists()
+        assert (snap_dir / "platforms" / "pairing" / "discord-approved.json").exists()
+        assert (snap_dir / "pairing" / "matrix-approved.json").exists()
+        assert (snap_dir / "feishu_comment_pairing.json").exists()
+
+        with open(snap_dir / "manifest.json") as f:
+            meta = json.load(f)
+        files = meta["files"]
+        assert "platforms/pairing/telegram-approved.json" in files
+        assert "platforms/pairing/discord-approved.json" in files
+        assert "pairing/matrix-approved.json" in files
+        assert "feishu_comment_pairing.json" in files
+
+    def test_restore_recovers_pairing_data(self, hermes_home):
+        """After restore, deleted pairing files reappear with original content."""
+        from hermes_cli.backup import create_quick_snapshot, restore_quick_snapshot
+
+        pairing_dir = hermes_home / "platforms" / "pairing"
+        pairing_dir.mkdir(parents=True)
+        approved = pairing_dir / "telegram-approved.json"
+        approved.write_text('{"12345": {"user_name": "alice"}}')
+        feishu = hermes_home / "feishu_comment_pairing.json"
+        feishu.write_text('{"doc_abc": {"allow_from": ["user_xyz"]}}')
+
+        snap_id = create_quick_snapshot(hermes_home=hermes_home)
+        assert snap_id is not None
+
+        # Simulate the disaster — user loses both pairing files.
+        approved.unlink()
+        feishu.unlink()
+        assert not approved.exists()
+        assert not feishu.exists()
+
+        assert restore_quick_snapshot(snap_id, hermes_home=hermes_home) is True
+        assert approved.exists()
+        assert '"alice"' in approved.read_text()
+        assert feishu.exists()
+        assert '"user_xyz"' in feishu.read_text()
+
+    def test_empty_pairing_dir_does_not_fail(self, hermes_home):
+        """An empty pairing directory should be silently skipped."""
+        from hermes_cli.backup import create_quick_snapshot
+
+        (hermes_home / "platforms" / "pairing").mkdir(parents=True)
+        # Directory exists but contains no files.
+        snap_id = create_quick_snapshot(hermes_home=hermes_home)
+        # Other state still present → snapshot succeeds.
+        assert snap_id is not None