refactor(dbt): migrate to domain-scoped schema names

- Create generate_schema_name macro to use custom schema names directly
- Update dbt_project.yml schemas: staging→stg_toronto, intermediate→int_toronto, marts→mart_toronto
- Add dbt/macros/toronto/ directory for future domain-specific macros
- Fix documentation drift in PROJECT_REFERENCE.md (load-data-only→load-toronto-only)
- Update DATABASE_SCHEMA.md with new schema names
- Update CLAUDE.md database schemas table
- Update adding-dashboard.md runbook with domain-scoped pattern

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CLAUDE.md

@@ -208,9 +208,9 @@ The codebase is structured to support multiple dashboard projects:
 |--------|---------|
 | `public` | Shared dimensions (dim_time) |
 | `raw_toronto` | Toronto-specific raw/dimension tables |
-| `staging` | dbt staging views |
-| `intermediate` | dbt intermediate views |
-| `marts` | dbt mart tables |
+| `stg_toronto` | Toronto dbt staging views |
+| `int_toronto` | Toronto dbt intermediate views |
+| `mart_toronto` | Toronto dbt mart tables |
 
 ### Geographic Reality (Toronto Housing)