refactor(admissions): rename published_admission_number to places_offered

The staging model aliased EES's total_number_places_offered column as
published_admission_number, but PAN is the school's published capacity
(not exposed by EES at school level) — what we actually have is the
count of places offered in a given admissions round. The misnomer
propagated to the mart, SQLAlchemy model, API response, TS types, and
UI copy ("places per year", "(PAN)").

Rename end-to-end and fix the UI labels:
  - "29 places for 42 first-choice applications"
      → "29 places offered for 42 first-choice applications"
  - "Reception/Year 7 places per year"
      → "Reception/Year 7 places offered"
  - drop the misleading "(PAN)" suffix in the secondary view

Also add a comment in stg_ees_admissions clarifying this is the number
of places offered, not PAN. Requires dbt to rebuild fact_admissions
(marts are materialized as tables) before the backend can start.

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

pipeline/transform/models/marts/fact_admissions.sql

@@ -4,7 +4,7 @@ select
     urn,
     year,
     school_phase,
-    published_admission_number,
+    places_offered,
     total_applications,
     first_preference_applications,
     first_preference_offers,

pipeline/transform/models/staging/stg_ees_admissions.sql

@@ -18,7 +18,11 @@ renamed as (
         entry_year,
 
         -- Places and offers
-        {{ safe_numeric('total_number_places_offered') }}::integer as published_admission_number,
+        -- places_offered: number of places the school actually offered in this
+        -- year's admissions round. NOT the Published Admission Number (PAN),
+        -- which is the school's published capacity — EES does not expose PAN
+        -- at school level, so we use the count of offers as the best proxy.
+        {{ safe_numeric('total_number_places_offered') }}::integer as places_offered,
         {{ safe_numeric('number_preferred_offers') }}::integer as total_offers,
         {{ safe_numeric('number_1st_preference_offers') }}::integer as first_preference_offers,
         {{ safe_numeric('number_2nd_preference_offers') }}::integer as second_preference_offers,