feat(server): add is_test_account + marks_as_test schema

New columns support separating soak-harness test traffic from real
user traffic in stats queries. Rebuilds leaderboard_overall matview
to include is_test_account so the fast path stays filterable.

Migration is idempotent via DO $$ / IF NOT EXISTS blocks inside
SCHEMA_SQL, which runs on every server startup — same mechanism
every existing post-v1 column migration uses.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/stores/user_store.py

@@ -95,6 +95,19 @@ BEGIN
                    WHERE table_name = 'users_v2' AND column_name = 'last_seen_at') THEN
         ALTER TABLE users_v2 ADD COLUMN last_seen_at TIMESTAMPTZ;
     END IF;
+    IF NOT EXISTS (SELECT 1 FROM information_schema.columns
+                   WHERE table_name = 'users_v2' AND column_name = 'is_test_account') THEN
+        ALTER TABLE users_v2 ADD COLUMN is_test_account BOOLEAN DEFAULT FALSE;
+    END IF;
+END $$;
+
+-- Add marks_as_test to invite_codes if not exists
+DO $$
+BEGIN
+    IF NOT EXISTS (SELECT 1 FROM information_schema.columns
+                   WHERE table_name = 'invite_codes' AND column_name = 'marks_as_test') THEN
+        ALTER TABLE invite_codes ADD COLUMN marks_as_test BOOLEAN DEFAULT FALSE;
+    END IF;
 END $$;
 
 -- Admin audit log table
@@ -296,14 +309,14 @@ CREATE TABLE IF NOT EXISTS system_metrics (
 );
 
 -- Leaderboard materialized view (refreshed periodically)
--- Drop and recreate if missing rating column (v3.1.0 migration)
+-- Drop and recreate if missing is_test_account column (soak harness migration)
 DO $$
 BEGIN
     IF EXISTS (SELECT 1 FROM pg_matviews WHERE matviewname = 'leaderboard_overall') THEN
-        -- Check if rating column exists in the view
+        -- Check if is_test_account column exists in the view
         IF NOT EXISTS (
             SELECT 1 FROM information_schema.columns
-            WHERE table_name = 'leaderboard_overall' AND column_name = 'rating'
+            WHERE table_name = 'leaderboard_overall' AND column_name = 'is_test_account'
         ) THEN
             DROP MATERIALIZED VIEW leaderboard_overall;
         END IF;
@@ -315,6 +328,7 @@ BEGIN
             SELECT
                 u.id as user_id,
                 u.username,
+                COALESCE(u.is_test_account, FALSE) as is_test_account,
                 s.games_played,
                 s.games_won,
                 ROUND(s.games_won::numeric / NULLIF(s.games_played, 0) * 100, 1) as win_rate,
@@ -342,6 +356,8 @@ CREATE INDEX IF NOT EXISTS idx_users_reset ON users_v2(reset_token) WHERE reset_
 CREATE INDEX IF NOT EXISTS idx_users_guest ON users_v2(guest_id) WHERE guest_id IS NOT NULL;
 CREATE INDEX IF NOT EXISTS idx_users_active ON users_v2(is_active) WHERE deleted_at IS NULL;
 CREATE INDEX IF NOT EXISTS idx_users_banned ON users_v2(is_banned) WHERE is_banned = TRUE;
+CREATE INDEX IF NOT EXISTS idx_users_test_account ON users_v2(is_test_account)
+    WHERE is_test_account = TRUE;
 
 CREATE INDEX IF NOT EXISTS idx_sessions_user ON user_sessions(user_id);
 CREATE INDEX IF NOT EXISTS idx_sessions_token ON user_sessions(token_hash);