feat: complete Phase 4 combat/hunting system

- Add content migration (003_content.sql): zones, monsters, items, loot tables
- Add inventory migration (004_inventory.sql) and logs migration (006_logs.sql)
- Add Mulberry32 PRNG (src/utils/rng.js) for deterministic combat
- Add combat system (src/game/combat.js) with turn order, crit, mage bonus, 20-round cap
- Add rewards/loot system (src/game/rewards.js) and leveling (src/game/leveling.js)
- Add hunt endpoint (POST /api/hunt) with full combat flow in DB transaction
- Add hunt integration tests and unit tests for rewards/leveling/combat
- Fix session middleware to use memory store in tests (avoids cleanup hang)
- Fix huntService transaction (db.transaction() returns wrapper, must call separately)
- Add huntService to helpers.js cache invalidation for test isolation

tests/helpers.js

@@ -5,6 +5,7 @@ const os = require('os');
 let tmpDir;
 let dbPath;
 let server;
+let dbRef;
 
 function createFreshApp() {
   process.env.DB_PATH = dbPath;
@@ -14,6 +15,7 @@ function createFreshApp() {
     require.resolve('../src/config'),
     require.resolve('../src/middleware/session'),
     require.resolve('../src/services/authService'),
+    require.resolve('../src/services/huntService'),
     require.resolve('../src/app'),
     require.resolve('../scripts/migrate'),
   ];
@@ -24,6 +26,10 @@ function createFreshApp() {
   const { runMigrations } = require('../scripts/migrate');
   runMigrations();
 
+  // Capture the DB instance before creating the app (session store uses it)
+  const dbModule = require('../src/db');
+  dbRef = dbModule.getDb();
+
   const { createApp } = require('../src/app');
   return createApp();
 }
@@ -46,13 +52,23 @@ async function setup() {
 function teardown() {
   return new Promise((resolve) => {
     if (server) {
-      // Force-close all connections and the server to avoid hanging on session store interval
+      // Close server first to stop accepting connections
       try { server.closeAllConnections(); } catch (_) {}
       server.close(() => {
         server = null;
+        // Then close DB to stop session store's cleanup interval
+        if (dbRef) {
+          try { dbRef.close(); } catch (_) {}
+          dbRef = null;
+        }
         resolve();
       });
     } else {
+      // No server, just close DB
+      if (dbRef) {
+        try { dbRef.close(); } catch (_) {}
+        dbRef = null;
+      }
       resolve();
     }
   });