feat(transform): add three pSEO serving models — city costs, country overview, city pricing

- pseo_city_costs_de: unblocks city-cost-de template (~600 city pages),
  joins city_market_profile + planner_defaults, includes camelCase calc
  override columns (ratePeak, rateOffPeak, utilTarget, dblCourts, country)
- pseo_country_overview: per-country hub aggregating from pseo_city_costs_de,
  includes top_city_slugs/names lists for internal linking
- pseo_city_pricing: per-city pricing pages requiring >= 2 Playtomic venues,
  includes P25/P75 price range and occupancy

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

transform/sqlmesh_padelnomics/models/serving/pseo_city_pricing.sql

@@ -0,0 +1,44 @@
+-- pSEO article data: per-city padel court pricing.
+-- One row per city — consumed by the city-pricing.md.jinja template.
+-- Joins venue_pricing_benchmarks (real Playtomic data) with city_market_profile
+-- (population, venue count, country metadata).
+--
+-- Stricter filter than pseo_city_costs_de: requires >= 2 venues with real
+-- pricing data so pricing articles are always data-backed.
+
+MODEL (
+  name serving.pseo_city_pricing,
+  kind FULL,
+  cron '@daily',
+  grain city_slug
+);
+
+SELECT
+  -- City identity (from city_market_profile, which has the canonical city_slug)
+  c.city_slug,
+  c.city_name,
+  c.country_code,
+  c.country_name_en,
+  c.country_slug,
+  -- Market context
+  c.population,
+  c.padel_venue_count,
+  c.venues_per_100k,
+  c.market_score,
+  -- Pricing benchmarks (from Playtomic availability data)
+  vpb.median_hourly_rate,
+  vpb.median_peak_rate,
+  vpb.median_offpeak_rate,
+  vpb.hourly_rate_p25,
+  vpb.hourly_rate_p75,
+  vpb.median_occupancy_rate,
+  vpb.venue_count,
+  vpb.price_currency,
+  CURRENT_DATE AS refreshed_date
+FROM serving.venue_pricing_benchmarks vpb
+-- Join city_market_profile to get the canonical city_slug and country metadata
+INNER JOIN serving.city_market_profile c
+  ON  vpb.country_code = c.country_code
+  AND LOWER(TRIM(vpb.city)) = LOWER(TRIM(c.city_name))
+-- Only cities with enough venues for meaningful pricing statistics
+WHERE vpb.venue_count >= 2