Fix SQLMesh config to use correct Pulumi ESC env var names

- Update secret token: CLOUDFLARE_API_TOKEN → R2_ADMIN_API_TOKEN
- Update warehouse name: R2_WAREHOUSE_NAME → ICEBERG_WAREHOUSE_NAME
- Update endpoint: ICEBERG_REST_URI → ICEBERG_CATALOG_URI

- Remove CREATE SCHEMA and USE statements
  - DuckDB has bug with Iceberg REST: missing Content-Type header
  - Schema creation via SQL currently not supported
  - Models will use fully-qualified table names instead

Successfully tested with real R2 credentials:
- Iceberg catalog attachment works ✓
- Plan dry-run executes ✓
- Only fails on missing source data (expected) ✓

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

transform/sqlmesh_materia/config.yaml

@@ -12,7 +12,7 @@ gateways:
       secrets:
         r2_secret:
           type: iceberg
-          token: "{{ env_var('CLOUDFLARE_API_TOKEN') }}"
+          token: "{{ env_var('R2_ADMIN_API_TOKEN') }}"
 
 default_gateway: prod
 
@@ -22,9 +22,10 @@ default_gateway: prod
 # https://developers.cloudflare.com/r2/data-catalog/config-examples/duckdb/
 
 before_all:
-  - "ATTACH '{{ env_var('R2_WAREHOUSE_NAME', 'materia') }}' AS catalog (TYPE ICEBERG, ENDPOINT '{{ env_var('ICEBERG_REST_URI') }}', SECRET r2_secret);"
-  - CREATE SCHEMA IF NOT EXISTS catalog.materia;
-  - USE catalog.materia;
+  - "ATTACH '{{ env_var('ICEBERG_WAREHOUSE_NAME') }}' AS catalog (TYPE ICEBERG, ENDPOINT '{{ env_var('ICEBERG_CATALOG_URI') }}', SECRET r2_secret);"
+  # Note: CREATE SCHEMA has a DuckDB/Iceberg bug (missing Content-Type header)
+  # Schema must be pre-created in R2 Data Catalog via Cloudflare dashboard or API
+  # For now, skip USE statement and rely on fully-qualified table names in models
 
 # --- Model Defaults ---
 # https://sqlmesh.readthedocs.io/en/stable/reference/model_configuration/#model-defaults