fix: reset SERIAL sequences after SQLite migration to prevent UniqueViolation

Migration script now resets SERIAL sequences (audit_log, context_files, etc.)
to max(existing_id) after copying rows. Without this, the sequence is still at
its post-schema-creation value and every INSERT hits a duplicate key error.

app/src/ctxd/migrate_sqlite_to_pg.py

@@ -179,6 +179,23 @@ def migrate():
     print(f"  context_files: {fts_cf} entries")
     print(f"  user_profiles: {fts_up} entries")
 
+    # Step 4: Reset SERIAL sequences to max(existing_id) + 1
+    print()
+    print("Resetting SERIAL sequences...")
+    for table, col in [
+        ("audit_log", "entry_id"),
+        ("context_files", "file_id"),
+        ("project_permissions", "id"),
+        ("reviews", "review_id"),
+        ("workspace_files", "file_id"),
+    ]:
+        try:
+            pconn.execute(f"SELECT setval(pg_get_serial_sequence('{table}', '{col}'), COALESCE((SELECT MAX({col}) FROM {table}), 1))")
+            print(f"  {table}.{col}: seq reset")
+        except Exception as e:
+            print(f"  {table}.{col}: skipped ({e})")
+    pconn.commit()
+
     print()
     print("=" * 60)
     print(f"Migration complete! {total_rows} total rows migrated.")