feat(pipeline): add Meltano + dbt + Airflow ELT pipeline scaffold

Replaces the hand-rolled integrator with a production-grade ELT pipeline
using Meltano (Singer taps), dbt Core (medallion architecture), and
Apache Airflow (orchestration). Adds Typesense for search and PostGIS
for geospatial queries.

- 6 custom Singer taps (GIAS, EES, Ofsted, Parent View, FBIT, IDACI)
- dbt project: 12 staging, 5 intermediate, 12 mart models
- 3 Airflow DAGs (daily/monthly/annual schedules)
- Typesense sync + batch geocoding scripts
- docker-compose: add Airflow, Typesense; upgrade to PostGIS
- Portainer stack definition matching live deployment topology

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

pipeline/transform/macros/chain_lineage.sql

@@ -0,0 +1,36 @@
+-- Macro: Generate a CTE that unions current and predecessor data for a given source
+
+{% macro chain_lineage(source_ref, urn_col='urn', year_col='year') %}
+
+with current_data as (
+    select
+        {{ urn_col }} as current_urn,
+        {{ urn_col }} as source_urn,
+        *
+    from {{ source_ref }}
+),
+
+predecessor_data as (
+    select
+        lin.current_urn,
+        src.{{ urn_col }} as source_urn,
+        src.*
+    from {{ source_ref }} src
+    inner join {{ ref('int_school_lineage') }} lin
+        on src.{{ urn_col }} = lin.predecessor_urn
+    where not exists (
+        select 1 from {{ source_ref }} curr
+        where curr.{{ urn_col }} = lin.current_urn
+          and curr.{{ year_col }} = src.{{ year_col }}
+    )
+),
+
+combined as (
+    select * from current_data
+    union all
+    select * from predecessor_data
+)
+
+select * from combined
+
+{% endmacro %}

pipeline/transform/macros/parse_ofsted_grade.sql

@@ -0,0 +1,13 @@
+-- Macro: Parse Ofsted grade from various text/numeric representations
+
+{% macro parse_ofsted_grade(column) %}
+    case
+        when {{ column }}::text in ('1', 'Outstanding') then 1
+        when {{ column }}::text in ('2', 'Good') then 2
+        when {{ column }}::text in ('3', 'Requires improvement', 'Requires Improvement', 'Satisfactory') then 3
+        when {{ column }}::text in ('4', 'Inadequate') then 4
+        when {{ column }}::text in ('9', 'SWK', 'Serious Weaknesses') then 4
+        when {{ column }}::text in ('SM', 'Special Measures') then 4
+        else null
+    end
+{% endmacro %}

pipeline/transform/macros/validate_uk_coordinates.sql

@@ -0,0 +1,8 @@
+-- Macro: Validate that latitude/longitude fall within UK bounding box
+
+{% macro validate_uk_coordinates(lat_col, lng_col) %}
+    (
+        {{ lat_col }} between 49.0 and 61.0
+        and {{ lng_col }} between -8.0 and 2.0
+    )
+{% endmacro %}