chore: remove the Ofsted Parent View feature end to end

Removes the 'What Parents Say' section and all supporting elements:

Frontend:
- Drop the OfstedParentView type, the parent_view field, the survey
  section and the 'X% would recommend' callouts in the primary and
  secondary detail views, the Parents nav item, and the parent-view CSS.

Backend:
- Remove the FactParentView model, its loading in data_loader, and
  parent_view from the school-details API response.
- Bump SCHEMA_VERSION to 6 and add an idempotent drop step
  (DROP TABLE IF EXISTS marts.fact_parent_view) to the CLI migration;
  add scripts/sql/drop_fact_parent_view.sql to apply directly to the
  dbt-owned marts DBs on staging and prod.

Pipeline:
- Delete the stg_parent_view + fact_parent_view dbt models and their
  source/schema entries, the tap-uk-parent-view Meltano extractor, and
  the monthly Parent View DAG; drop it from the Dockerfile and the
  staging bootstrap docs.

The rest of dbt (which builds every mart the app reads) is untouched.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/app.py

@@ -572,7 +572,7 @@ async def get_school_details(request: Request, urn: int):
     # Get latest info for the school
     latest = school_data.iloc[-1]
 
-    # Fetch supplementary data (Ofsted, Parent View, admissions, etc.)
+    # Fetch supplementary data (Ofsted, admissions, etc.)
     from .database import SessionLocal
     supplementary = {}
     try:
@@ -605,7 +605,6 @@ async def get_school_details(request: Request, urn: int):
         "yearly_data": clean_for_json(school_data),
         # Supplementary data (null if not yet populated by Kestra)
         "ofsted": supplementary.get("ofsted"),
-        "parent_view": supplementary.get("parent_view"),
         "census": supplementary.get("census"),
         "admissions": supplementary.get("admissions"),
         "admissions_history": supplementary.get("admissions_history") or [],