feat(convert): integrate process metrics into JSON and SQLite converters

- add process_metrics function to record peak RSS and CPU time
- update JSON converter to include metrics in completion marker
- modify SQLite converter to utilize new metrics for performance tracking
- enhance storage size updates with locking mechanism for concurrent access

common/queries/__init__.py

@@ -0,0 +1,15 @@
+"""Benchmark query implementations for the file-based formats (spec 08).
+
+One module per format (csv_queries, json_queries, rdf_queries), each with
+functions q1..q7 returning canonical result rows (see common/results.py).
+The runnable wrappers under out/bench/queries/ are generated by
+make_queries.py and delegate here. SQLite / PostgreSQL implementations are
+plain SQL files written by make_queries.py.
+
+The relational formats answer Q2/Q3/Q4/Q7 from the precomputed
+track_summary (their idiomatic strength); the file formats derive the same
+values from raw cycles via common/track_summary.py - identical algorithm,
+identical results (bench-methodology section 5).
+"""
+
+Q1_TRACK_CODE = "B722-W2-C13-T2"  # fixed benchmark track, spec 08