feat(compact): Access database compact & repair API + CLI

- API: POST /api/compact (optional body {"files": [...]})
- CLI: python main.py compact [--db FILE]
- Local path: rename → CompactDatabase(bak→src) → delete bak (zero copy)
- UNC path: copy to local temp → compact → copy back (avoids DAO segfault)
- Uses DAO DBEngine.CompactDatabase via pywin32 COM
- new dep: pywin32>=306

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

main.py

@@ -5,6 +5,7 @@ Run from the project root (no ``-m`` needed)::
     python main.py fullsync    [--db FILE] [--table NAME] [--clear-change-log]
     python main.py incremental [--loop] [--poll-interval N]
     python main.py compare     [--granularity count|ids] [--db FILE] [--table NAME] [--report PATH]
+    python main.py compact     [--db FILE]
 
 Configuration is hard-coded to ``config.yaml`` next to this script -- it is not
 a command-line argument, so all three blocks always use the same config (and
@@ -29,6 +30,7 @@ from sync.logging_setup import setup_logging
 from sync.fullsync import full_sync
 from sync import service
 from sync.compare import compare, any_mismatch, format_report, write_report
+from sync.compact import compact_files, _human
 
 CONFIG_PATH = os.path.join(os.path.dirname(os.path.abspath(__file__)), "config.yaml")
 log = logging.getLogger("main")
@@ -60,6 +62,9 @@ def _parse_args(argv):
     pc.add_argument("--table", help="limit to one table")
     pc.add_argument("--report", help="write the report to this file as well as stdout")
 
+    pcp = sub.add_parser("compact", help="compact & repair Access databases")
+    pcp.add_argument("--db", help="limit to one Access file (by FileMapping.file)")
+
     return p.parse_args(argv)
 
 
@@ -98,6 +103,16 @@ def main(argv=None) -> int:
             service.cycle(cfg)
         return 0
 
+    if args.command == "compact":
+        summary = compact_files(cfg, db_filter=args.db)
+        for r in summary.results:
+            if r.ok:
+                print(f"[OK]    {r.file}  {_human(r.before_bytes)} -> {_human(r.after_bytes)}  ({r.duration_s:.1f}s)")
+            else:
+                print(f"[FAIL]  {r.file}  {r.error}")
+        print(f"--- {summary.ok} OK, {summary.failed} FAIL, saved {_human(summary.saved_bytes)} ---")
+        return 0 if summary.all_ok else 1
+
     if args.command == "compare":
         results = compare(cfg, granularity=args.granularity,
                           db_filter=args.db, table_filter=args.table)