feat(#64): Improve the about page

supabase/migrations/20260110120001_create_update_stats_function.sql

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+-- Create function to calculate and update stats in the cache table
+-- This function runs the expensive queries and stores the results
+
+CREATE OR REPLACE FUNCTION update_and_get_stats()
+RETURNS TABLE (
+  pokemon_caught BIGINT,
+  total_users BIGINT,
+  completed_pokedexes BIGINT,
+  updated_at TIMESTAMPTZ
+)
+SECURITY DEFINER
+LANGUAGE plpgsql
+AS $$
+DECLARE
+  v_pokemon_caught BIGINT;
+  v_total_users BIGINT;
+  v_completed_pokedexes BIGINT;
+BEGIN
+  -- Calculate current stats: count of caught Pokémon
+  SELECT COUNT(*) INTO v_pokemon_caught
+  FROM catch_records
+  WHERE caught = true;
+
+  -- Calculate current stats: count of total users
+  SELECT COUNT(*) INTO v_total_users
+  FROM auth.users;
+
+  -- Calculate current stats: count of completed pokedexes
+  -- A pokedex is completed when all its entries have caught = true
+  SELECT COUNT(*) INTO v_completed_pokedexes
+  FROM (
+    SELECT pokedexId
+    FROM catch_records
+    GROUP BY pokedexId
+    HAVING COUNT(*) = COUNT(*) FILTER (WHERE caught = true)
+  ) completed;
+
+  -- Update cache using UPSERT pattern
+  INSERT INTO stats_cache (pokemon_caught, total_users, completed_pokedexes, updated_at)
+  VALUES (v_pokemon_caught, v_total_users, v_completed_pokedexes, NOW())
+  ON CONFLICT (id) DO UPDATE
+  SET pokemon_caught = EXCLUDED.pokemon_caught,
+      total_users = EXCLUDED.total_users,
+      completed_pokedexes = EXCLUDED.completed_pokedexes,
+      updated_at = NOW();
+
+  -- Return the stats
+  RETURN QUERY
+  SELECT v_pokemon_caught, v_total_users, v_completed_pokedexes, NOW() AS updated_at;
+END;
+$$;