fix(dbt): filter non-numeric URNs and trim whitespace in EES staging models

- Filter school_urn/time_period to '^[0-9]+$' to exclude "n/a" and other
  non-numeric values that caused integer cast failures in fact_admissions
- Add trim() to all school_urn/time_period casts to prevent whitespace
  variants producing duplicate urn+year rows in fact_ks2_performance

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

pipeline/transform/models/staging/stg_ees_admissions.sql

@@ -5,13 +5,15 @@
 
 with source as (
     select * from {{ source('raw', 'ees_admissions') }}
-    where school_urn is not null
+    -- Exclude rows where school_urn is null, empty, or non-numeric (e.g. "n/a" LA aggregates)
+    where school_urn ~ '^[0-9]+$'
+      and time_period ~ '^[0-9]+$'
 ),
 
 renamed as (
     select
-        cast(school_urn as integer) as urn,
-        cast(time_period as integer) as year,
+        cast(trim(school_urn) as integer) as urn,
+        cast(trim(time_period) as integer) as year,
         school_phase,
         entry_year,
 
@@ -30,14 +32,11 @@ renamed as (
         {{ safe_numeric('proportion_1stprefs_v_totaloffers') }} as first_preference_offer_pct,
 
         -- Derived: oversubscribed if 1st-preference applications > places offered
-        case
-            when {{ safe_numeric('times_put_as_1st_preference') }} is not null
-                 and {{ safe_numeric('total_number_places_offered') }} is not null
-                 and {{ safe_numeric('times_put_as_1st_preference') }}
-                     > {{ safe_numeric('total_number_places_offered') }}
-            then true
-            else false
-        end as oversubscribed,
+        -- Use already-cast columns to avoid repeating the regex expression
+        (
+            {{ safe_numeric('times_put_as_1st_preference') }}
+            > {{ safe_numeric('total_number_places_offered') }}
+        ) as oversubscribed,
 
         -- Context
         admissions_policy,

pipeline/transform/models/staging/stg_ees_ks2.sql

@@ -9,13 +9,14 @@
 
 with attainment as (
     select * from {{ source('raw', 'ees_ks2_attainment') }}
-    where school_urn is not null
+    where school_urn ~ '^[0-9]+$'
+      and time_period ~ '^[0-9]+$'
 ),
 
 pivoted as (
     select
-        cast(school_urn as integer) as urn,
-        cast(time_period as integer) as year,
+        cast(trim(school_urn) as integer) as urn,
+        cast(trim(time_period) as integer) as year,
 
         -- RWM combined (All pupils / Total)
         max(case when subject = 'Reading, writing and maths'
@@ -117,8 +118,8 @@ pivoted as (
 
 info as (
     select
-        cast(school_urn as integer) as urn,
-        cast(time_period as integer) as year,
+        cast(trim(school_urn) as integer) as urn,
+        cast(trim(time_period) as integer) as year,
         {{ safe_numeric('totpups') }}::integer as total_pupils,
         {{ safe_numeric('telig') }}::integer as eligible_pupils,
         {{ safe_numeric('ptfsm6cla1a') }} as disadvantaged_pct,

pipeline/transform/models/staging/stg_ees_ks4.sql

@@ -9,14 +9,15 @@
 
 with performance as (
     select * from {{ source('raw', 'ees_ks4_performance') }}
-    where school_urn is not null
+    where school_urn ~ '^[0-9]+$'
+      and time_period ~ '^[0-9]+$'
 ),
 
 -- Filter to all-pupils totals (one row per school per year)
 all_pupils as (
     select
-        cast(school_urn as integer) as urn,
-        cast(time_period as integer) as year,
+        cast(trim(school_urn) as integer) as urn,
+        cast(trim(time_period) as integer) as year,
         {{ safe_numeric('pupil_count') }}::integer as total_pupils,
 
         -- Attainment 8
@@ -53,8 +54,8 @@ all_pupils as (
 -- KS4 info table for context/demographics
 info as (
     select
-        cast(school_urn as integer) as urn,
-        cast(time_period as integer) as year,
+        cast(trim(school_urn) as integer) as urn,
+        cast(trim(time_period) as integer) as year,
         {{ safe_numeric('endks4_pupil_count') }}::integer as eligible_pupils,
         {{ safe_numeric('ks2_scaledscore_average') }} as prior_attainment_avg,
         {{ safe_numeric('sen_pupil_percent') }} as sen_pct,