Enable multi-edge-table indexing for code graph entities
## Summary
The compiler and indexer now support routing edges to different physical ClickHouse tables based on ontology configuration. All plumbing is in place (MR !889), but everything still routes to `gl_edge` until explicitly activated.
## What needs to happen
1. Declare `gl_code_edge` in `config/ontology/schema.yaml` under `settings.edge_tables` with column/storage/projection definitions
2. Set `table: gl_code_edge` on code-domain edge YAMLs: `DEFINES`, `IMPORTS`, `TARGETS` (and any other code-only edges)
3. Update `CodeTableNames::from_ontology` to use `ontology.edge_table_for_relationship("DEFINES")` instead of `ontology.edge_table()`
4. Update `graph_local.sql` to add the `gl_code_edge` table for local DuckDB mode
5. Bump `SCHEMA_VERSION`
6. Add data correctness integration tests with seeded data in both edge tables
7. Validate namespace deletion cleans both tables
8. Stage rollout: deploy to staging, verify edge writes land in correct tables, verify wildcard queries return complete results
## Context
- MR !889 wired multi-edge-table routing through the compiler (lower, optimize passes) and indexer (SDLC plan, namespace deletion)
- Code indexer has TODO comments marking the 1-line changes needed
- Wildcard queries already emit UNION ALL across all declared edge tables
- All existing tests pass unchanged (zero behavioral change until activation)
issue