fix(dbt): stub rc_* columns as NULL in stg_ofsted_inspections

tap-uk-ofsted schema only declares OEIF columns; rc_* (Report Card)
columns were never emitted so they don't exist in raw.ofsted_inspections.
Replace column references with NULL::text until the actual CSV column
names for the post-Nov 2025 Report Card framework are confirmed and
added to the tap schema.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pipeline/transform/models/staging/stg_ofsted_inspections.sql

@@ -21,16 +21,17 @@ renamed as (
         cast(early_years_provision as integer)              as early_years_provision,
         cast(sixth_form_provision as integer)               as sixth_form_provision,
 
-        -- Report Card fields (populated for post-Nov 2025 inspections)
-        rc_safeguarding_met,
-        rc_inclusion,
-        rc_curriculum_teaching,
-        rc_achievement,
-        rc_attendance_behaviour,
-        rc_personal_development,
-        rc_leadership_governance,
-        rc_early_years,
-        rc_sixth_form,
+        -- Report Card fields (post-Nov 2025 framework)
+        -- TODO: add rc_* columns to tap-uk-ofsted schema once CSV column names are confirmed
+        null::text as rc_safeguarding_met,
+        null::text as rc_inclusion,
+        null::text as rc_curriculum_teaching,
+        null::text as rc_achievement,
+        null::text as rc_attendance_behaviour,
+        null::text as rc_personal_development,
+        null::text as rc_leadership_governance,
+        null::text as rc_early_years,
+        null::text as rc_sixth_form,
 
         report_url
     from source