feat: Migrate Arbiter and Modpack Version Checker to monorepo

WHAT WAS DONE:
- Migrated Arbiter (discord-oauth-arbiter) code to services/arbiter/
- Migrated Modpack Version Checker code to services/modpack-version-checker/
- Created .env.example for Arbiter with all required environment variables
- Moved systemd service file to services/arbiter/deploy/
- Organized directory structure per Gemini monorepo recommendations

WHY:
- Consolidate all service code in one repository
- Prepare for Gemini code review (Panel v1.12 compatibility check)
- Enable service-prefixed Git tagging (arbiter-v2.1.0, modpack-v1.0.0)
- Support npm workspaces for shared dependencies

SERVICES MIGRATED:
1. Arbiter (Discord OAuth bot) - Originally written by Gemini + Claude
   - Full source code from ops-manual docs/implementation/
   - Created comprehensive .env.example
   - Ready for Panel v1.12 compatibility verification

2. Modpack Version Checker (Python CLI tool)
   - Full source code from ops-manual docs/tasks/
   - Written for Panel v1.11, needs Gemini review for v1.12
   - Never had code review before

STILL TODO:
- Whitelist Manager - Pull from Billing VPS (38.68.14.188)
  - Currently deployed and running
  - Needs Panel v1.12 API compatibility fix (Task #86)
  - Requires SSH access to pull code

NEXT STEPS:
- Gemini code review for Panel v1.12 API compatibility
- Create package.json for each service
- Test npm workspaces integration
- Deploy after verification

FILES:
- services/arbiter/ (25 new files, full application)
- services/modpack-version-checker/ (21 new files, full application)

Signed-off-by: The Golden Chronicler <claude@firefrostgaming.com>

services/arbiter/src/database.js

@@ -0,0 +1,46 @@
+// src/database.js
+// SQLite database initialization and maintenance for Firefrost Arbiter
+
+const Database = require('better-sqlite3');
+const db = new Database('linking.db');
+
+// Create tables if they don't exist
+db.exec(`
+  CREATE TABLE IF NOT EXISTS link_tokens (
+    token TEXT PRIMARY KEY,
+    email TEXT NOT NULL,
+    tier TEXT NOT NULL,
+    subscription_id TEXT NOT NULL,
+    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+    used INTEGER DEFAULT 0
+  )
+`);
+
+db.exec(`
+  CREATE TABLE IF NOT EXISTS audit_logs (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    admin_id TEXT NOT NULL,
+    target_user TEXT NOT NULL,
+    action TEXT NOT NULL,
+    reason TEXT NOT NULL,
+    timestamp DATETIME DEFAULT CURRENT_TIMESTAMP
+  )
+`);
+
+// Cleanup function - removes tokens older than 24 hours
+function cleanupExpiredTokens() {
+    const stmt = db.prepare(`
+        DELETE FROM link_tokens 
+        WHERE created_at < datetime('now', '-1 day')
+    `);
+    const info = stmt.run();
+    console.log(`[Database] Cleaned up ${info.changes} expired tokens.`);
+}
+
+// Run cleanup once every 24 hours (86400000 ms)
+setInterval(cleanupExpiredTokens, 86400000);
+
+// Run cleanup on startup to clear any that expired while app was down
+cleanupExpiredTokens();
+
+module.exports = db;