feat: Playtomic pricing/occupancy pipeline + email i18n + audience restructure

Three workstreams:

1. Playtomic full data extraction & transform pipeline:
   - Expand venue bounding boxes from 4 to 23 regions (global coverage)
   - New staging models for court resources, opening hours, and slot-level
     availability with real prices from the Playtomic API
   - Foundation fact tables for venue capacity and daily occupancy/revenue
   - City-level pricing benchmarks replacing hardcoded country estimates
   - Planner defaults now use 3-tier cascade: city data → country → fallback

2. Transactional email i18n:
   - _t() helper in worker.py with ~70 translation keys (EN + DE)
   - All 8 email handlers translated, lang passed in task payloads

3. Resend audiences restructured to 3 named audiences (free plan limit)

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

transform/sqlmesh_padelnomics/models/foundation/fct_venue_capacity.sql

@@ -0,0 +1,45 @@
+-- Venue capacity: total bookable court-hours per day and week.
+-- Derived from active court count × opening hours.
+-- Used as the denominator for occupancy rate in fct_daily_availability.
+--
+-- One row per venue (Playtomic tenant).
+
+MODEL (
+  name foundation.fct_venue_capacity,
+  kind FULL,
+  cron '@daily',
+  grain tenant_id
+);
+
+WITH weekly_hours AS (
+  SELECT
+    tenant_id,
+    SUM(hours_open)                               AS hours_open_per_week,
+    AVG(hours_open)                               AS avg_hours_open_per_day,
+    COUNT(*)                                      AS days_open_per_week
+  FROM staging.stg_playtomic_opening_hours
+  GROUP BY tenant_id
+),
+court_counts AS (
+  SELECT
+    tenant_id,
+    COUNT(*)                                      AS active_court_count
+  FROM staging.stg_playtomic_resources
+  WHERE is_active = TRUE
+  GROUP BY tenant_id
+)
+SELECT
+  v.tenant_id,
+  v.country_code,
+  v.city,
+  cc.active_court_count,
+  ROUND(wh.hours_open_per_week, 1)                AS hours_open_per_week,
+  ROUND(wh.avg_hours_open_per_day, 1)             AS avg_hours_open_per_day,
+  wh.days_open_per_week,
+  -- Total bookable court-hours per day (capacity denominator for occupancy)
+  ROUND(cc.active_court_count * wh.avg_hours_open_per_day, 1)  AS capacity_court_hours_per_day,
+  -- Total bookable court-hours per week
+  ROUND(cc.active_court_count * wh.hours_open_per_week, 1)     AS capacity_court_hours_per_week
+FROM staging.stg_playtomic_venues v
+JOIN court_counts cc ON v.tenant_id = cc.tenant_id
+JOIN weekly_hours wh ON v.tenant_id = wh.tenant_id