feat(convert): add task 05 sqlite converter with variant B keys" -m "- convert: convert_sqlite.py builds tribo.db (composite PKs, enforced FKs, Q1-Q7 indexes, track_summary)

- tools: common/track_summary.py fixes the cross-engine steady-state algorithm
- rules: db-sql-schema records the FK enforcement decision and track_summary definition
- specs: 05 aligned with data-naming-units, simtra_profiles added
- docs: FK key-schema study added under docs/research/, README updated
- replace manual CSV reading with CorpusReader for better data handling
- streamline argument parsing and dependency checks using common pipeline functions
- enhance marker writing for task completion tracking
- remove unused regex and validation error classes for cleaner code

README.md

@@ -61,7 +61,7 @@ machine (no parallel work). Every task writes a completion marker
 | 02 Process flow diagrams | `make_process_flow.py` | `out/report/process_flow.md`, `out/report/diagrams/` | implemented |
 | 03 CSV data generation | `generate_data.py` | `out/csv/` tree + `MANIFEST.csv` | implemented |
 | 04 Convert to JSON-LD | `convert_json.py` | `out/json/full/`, `out/json/hybrid/dataset.jsonld` | implemented |
-| 05 Convert to SQLite | `convert_sqlite.py` | `out/sqlite/tribo.db` | planned |
+| 05 Convert to SQLite | `convert_sqlite.py` | `out/sqlite/tribo.db` | implemented |
 | 06 Convert to PostgreSQL | `convert_postgresql.py` | live `tribo` DB + `out/pg/tribo.dump` | planned |
 | 07 Convert to RDF | `convert_rdf.py` | `out/rdf/dataset.nt.gz`, oxigraph store | planned |
 | 08 Benchmark queries | `make_queries.py` | `out/bench/queries/`, `out/bench/expected/` | planned |
@@ -142,6 +142,7 @@ measurement counts. See
 docs/
   specs/        task specifications 00-11 (WHAT to build)
   rules/        binding conventions (HOW work is done)
+  research/     measured design studies (e.g. FK key-schema study)
   examples/     imported reference materials (not binding)
 out/            ALL generated artifacts (git-ignored, reproducible):
   config/ csv/ json/ sqlite/ pg/ rdf/ bench/ report/ .done/
@@ -150,6 +151,7 @@ make_lab_config.py    task 01 entry script (one script per task, repo root)
 make_process_flow.py  task 02 entry script
 generate_data.py      task 03 entry script
 convert_json.py       task 04 entry script
+convert_sqlite.py     task 05 entry script
 requirements.txt      closed dependency list (docs/rules/code-python-style.md)
 ```