feat(db): add 'python -m app.db' CLI for migrations

D006: idempotent --migrate, --info (schema version + row counts), and --path.
Used by deploy.sh to bring the DB up to date after a git pull without the web
server running.

app/db/__main__.py

@@ -0,0 +1,74 @@
+#!/usr/bin/env python3
+"""CLI entry point for the SQLite store.
+
+Usage:
+    python -m app.db --migrate        applies pending migrations (idempotent)
+    python -m app.db --info           prints schema version + table counts, exits
+    python -m app.db --path           prints the resolved DB path, exits
+
+Used by ``deploy.sh`` (D004) to ensure the DB is up to date after a ``git pull``
+without needing the web server up.
+"""
+
+from __future__ import annotations
+
+import argparse
+import sys
+
+from ..utils.constants import DATA_DB_PATH
+from .schema import SCHEMA_VERSION, apply_migrations
+
+
+def main(argv: list[str] | None = None) -> int:
+    parser = argparse.ArgumentParser(
+        prog="python -m app.db",
+        description="Intrusion-detection SQLite store utilities.")
+    parser.add_argument("--migrate", action="store_true",
+                        help="apply pending schema migrations (idempotent)")
+    parser.add_argument("--info", action="store_true",
+                        help="print schema version + table/row counts")
+    parser.add_argument("--path", action="store_true",
+                        help="print the resolved DB path and exit")
+    args = parser.parse_args(argv)
+
+    if args.path:
+        print(DATA_DB_PATH)
+        return 0
+
+    from . import get_connection
+
+    conn = get_connection()
+    current = conn.execute("PRAGMA user_version").fetchone()[0]
+
+    if args.info:
+        counts = {}
+        tables = conn.execute(
+            "SELECT name FROM sqlite_master WHERE type='table' "
+            "AND name NOT LIKE 'sqlite_%' ORDER BY name").fetchall()
+        for t in tables:
+            name = t["name"]
+            try:
+                counts[name] = conn.execute(
+                    f"SELECT COUNT(*) FROM \"{name}\"").fetchone()[0]
+            except Exception:
+                counts[name] = None
+        print(f"db_path:  {DATA_DB_PATH}")
+        print(f"version:  {current} (latest {SCHEMA_VERSION})")
+        print("tables:")
+        for name, n in counts.items():
+            print(f"  {name:<32} {n} rows")
+        return 0
+
+    if args.migrate or current < SCHEMA_VERSION:
+        before = current
+        apply_migrations(conn)
+        print(f"schema version {before} -> "
+              f"{conn.execute('PRAGMA user_version').fetchone()[0]}")
+        return 0
+
+    print(f"schema is already up to date (version {current})")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())