fix(pipeline): expand GIAS schema, handle empty strings, scope DAG selectors

- Declare all 34 columns needed by dbt in GIAS tap schema (target-postgres
  only persists columns present in the Singer schema message)
- Use nullif() for empty-string-to-integer/date casts in staging models
- Scope daily DAG dbt build to GIAS models only (stg_gias_establishments+
  stg_gias_links+) to avoid errors on unloaded sources
- Scope annual EES DAG similarly; remove redundant dbt test steps
- Make dim_school gracefully handle missing int_ofsted_latest table

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

pipeline/plugins/extractors/tap-uk-gias/tap_uk_gias/tap.py

@@ -25,9 +25,9 @@ class GIASEstablishmentsStream(Stream):
     primary_keys = ["URN"]
     replication_key = None
 
-    # Schema is wide (~250 columns); we declare key columns and pass through the rest
-    # All columns are read as strings from CSV; dbt staging models handle type casting.
-    # Only URN is cast to int in get_records() for the primary key.
+    # All columns used by dbt staging models must be declared here —
+    # target-postgres only persists columns present in the Singer schema.
+    # All non-PK columns are StringType; dbt handles type casting.
     schema = th.PropertiesList(
         th.Property("URN", th.IntegerType, required=True),
         th.Property("EstablishmentName", th.StringType),
@@ -38,6 +38,31 @@ class GIASEstablishmentsStream(Stream):
         th.Property("EstablishmentNumber", th.StringType),
         th.Property("EstablishmentStatus (name)", th.StringType),
         th.Property("Postcode", th.StringType),
+        th.Property("Gender (name)", th.StringType),
+        th.Property("ReligiousCharacter (name)", th.StringType),
+        th.Property("AdmissionsPolicy (name)", th.StringType),
+        th.Property("SchoolCapacity", th.StringType),
+        th.Property("NumberOfPupils", th.StringType),
+        th.Property("HeadTitle (name)", th.StringType),
+        th.Property("HeadFirstName", th.StringType),
+        th.Property("HeadLastName", th.StringType),
+        th.Property("TelephoneNum", th.StringType),
+        th.Property("SchoolWebsite", th.StringType),
+        th.Property("Street", th.StringType),
+        th.Property("Locality", th.StringType),
+        th.Property("Town", th.StringType),
+        th.Property("County (name)", th.StringType),
+        th.Property("OpenDate", th.StringType),
+        th.Property("CloseDate", th.StringType),
+        th.Property("Trusts (name)", th.StringType),
+        th.Property("Trusts (code)", th.StringType),
+        th.Property("UrbanRural (name)", th.StringType),
+        th.Property("ParliamentaryConstituency (name)", th.StringType),
+        th.Property("NurseryProvision (name)", th.StringType),
+        th.Property("Easting", th.StringType),
+        th.Property("Northing", th.StringType),
+        th.Property("StatutoryLowAge", th.StringType),
+        th.Property("StatutoryHighAge", th.StringType),
     ).to_dict()
 
     def get_records(self, context):