Add additive metadata tables and indexes for future staged exact-delta indexing: generations, file state, node/edge owners, symbol exports, import refs, and derived view freshness.
Keep this slice behavior-neutral. Normal store open migrates the schema, query-only open still does not create missing DBs, and writer-produced DBs remain minimal but migrate through cbm_store_open_path().
Validation: make -f Makefile.cbm build/c/test-runner; CBM_ONLY_SUITE=store_nodes ./build/c/test-runner; CBM_ONLY_SUITE=sqlite_writer ./build/c/test-runner; CBM_ONLY_SUITE=tool_consolidation ./build/c/test-runner; CBM_ONLY_SUITE=store_search ./build/c/test-runner; CBM_ONLY_SUITE=store_bulk ./build/c/test-runner; CBM_ONLY_SUITE=incremental ./build/c/test-runner; bash scripts/check-source-safety.sh; git diff --check.
Signed-off-by: Andrew Hundt <ATHundt@gmail.com>
