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/version.py

@@ -13,7 +13,7 @@ WHEN TO BUMP:
 """
 
 # Current schema version - increment when models change
-SCHEMA_VERSION = 5
+SCHEMA_VERSION = 6
 
 # Changelog for documentation
 SCHEMA_CHANGELOG = {
@@ -22,4 +22,5 @@ SCHEMA_CHANGELOG = {
     3: "Added supplementary data tables: ofsted, parent_view, census, admissions, sen_detail, phonics, deprivation, finance; GIAS columns on schools",
     4: "Added Ofsted Report Card columns to ofsted_inspections (new framework from Nov 2025)",
     5: "Apply ALTER TABLE additions for RC columns missed by create_all on existing tables",
+    6: "Removed the Ofsted Parent View feature: dropped fact_parent_view table and model",
 }