feat: Python supervisor + feature flags

Supervisor (replaces supervisor.sh):
- supervisor.py — cron-based pipeline orchestration, reads workflows.toml
  on every tick, runs due extractors in topological waves with parallel
  execution, then SQLMesh transform + serving export
- workflows.toml — workflow registry: overpass (monthly), eurostat (monthly),
  playtomic_tenants (weekly), playtomic_availability (daily),
  playtomic_recheck (hourly 6–23)
- padelnomics-supervisor.service — updated ExecStart to Python supervisor

Extraction enhancements:
- proxy.py — optional round-robin/sticky proxy rotation via PROXY_URLS env
- playtomic_availability.py — parallel fetch (EXTRACT_WORKERS), recheck mode
  (main_recheck) re-queries imminent slots for accurate occupancy measurement
- _shared.py — realistic browser User-Agent on all extractor sessions
- stg_playtomic_availability.sql — reads morning + recheck snapshots, tags each
- fct_daily_availability.sql — prefers recheck over morning for same slot

Feature flags (replaces WAITLIST_MODE env var):
- migration 0019 — feature_flags table, 5 initial flags:
  markets (on), payments/planner_export/supplier_signup/lead_unlock (off)
- core.py — is_flag_enabled() + feature_gate() decorator
- routes — payments, markets, planner_export, supplier_signup, lead_unlock gated
- admin flags UI — /admin/flags toggle page + nav link
- app.py — flag() injected as Jinja2 global

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

transform/sqlmesh_padelnomics/models/foundation/fct_daily_availability.sql

@@ -3,6 +3,10 @@
 -- per-day statistics, then calculates occupancy by comparing available hours
 -- against total capacity from fct_venue_capacity.
 --
+-- Recheck-aware occupancy: for each (tenant, resource, slot_start_time),
+-- prefer the latest snapshot (recheck > morning). A slot present in morning
+-- but absent in the recheck = booked between snapshots → more accurate occupancy.
+--
 -- Occupancy = 1 - (available_court_hours / capacity_court_hours_per_day)
 -- Revenue estimate = booked_court_hours × avg_price_of_available_slots
 --
@@ -15,14 +19,31 @@ MODEL (
   grain (snapshot_date, tenant_id)
 );
 
-WITH slot_agg AS (
+-- Prefer the latest snapshot for each slot:
+-- If a recheck exists for a (date, tenant, resource, start_time), use it.
+-- Otherwise fall back to the morning snapshot.
+WITH ranked_slots AS (
+  SELECT
+    a.*,
+    ROW_NUMBER() OVER (
+      PARTITION BY a.snapshot_date, a.tenant_id, a.resource_id, a.slot_start_time
+      ORDER BY
+        CASE WHEN a.snapshot_type = 'recheck' THEN 1 ELSE 2 END,
+        a.captured_at_utc DESC
+    ) AS rn
+  FROM staging.stg_playtomic_availability a
+  WHERE a.price_amount IS NOT NULL
+    AND a.price_amount > 0
+),
+latest_slots AS (
+  SELECT * FROM ranked_slots WHERE rn = 1
+),
+slot_agg AS (
   SELECT
     a.snapshot_date,
     a.tenant_id,
-    -- Slot counts: each row is one 60-min available slot on one court
     COUNT(*)                                              AS available_slot_count,
     COUNT(DISTINCT a.resource_id)                         AS courts_with_availability,
-    -- Available (unbooked) court-hours: slots are on 30-min increments for 60-min bookings
     -- Each available start_time represents a 60-min bookable window
     ROUND(COUNT(*) * 1.0, 2)                              AS available_court_hours,
     -- Pricing stats (60-min slots only)
@@ -42,9 +63,7 @@ WITH slot_agg AS (
     ), 2)                                                 AS median_price_offpeak,
     MAX(a.price_currency)                                 AS price_currency,
     MAX(a.captured_at_utc)                                AS captured_at_utc
-  FROM staging.stg_playtomic_availability a
-  WHERE a.price_amount IS NOT NULL
-    AND a.price_amount > 0
+  FROM latest_slots a
   GROUP BY a.snapshot_date, a.tenant_id
 )
 SELECT