feat: Add connection resilience with auto-reconnect and heartbeat

- Add UnityConnection class with exponential backoff reconnection
- Add ConnectionState enum (Disconnected, Connecting, Connected, Reconnecting)
- Add heartbeat/ping-pong mechanism to detect stale connections
- Emit connection state change events for UI feedback
- Refactor McpUnity to use new UnityConnection class
- Add Jest test suite with 14 tests for connection handling

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: PhilipLudington

Server~/jest.config.js

@@ -0,0 +1,30 @@
+/** @type {import('ts-jest').JestConfigWithTsJest} */
+export default {
+  preset: 'ts-jest/presets/default-esm',
+  testEnvironment: 'node',
+  extensionsToTreatAsEsm: ['.ts'],
+  moduleNameMapper: {
+    '^(\\.{1,2}/.*)\\.js$': '$1',
+  },
+  transform: {
+    '^.+\\.tsx?$': [
+      'ts-jest',
+      {
+        useESM: true,
+        isolatedModules: true,
+        tsconfig: {
+          target: 'ES2022',
+          module: 'ESNext',
+          moduleResolution: 'Node',
+          esModuleInterop: true,
+          strict: true,
+          skipLibCheck: true,
+          types: ['node', 'jest'],
+        },
+      },
+    ],
+  },
+  testMatch: ['**/__tests__/**/*.test.ts'],
+  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
+  testTimeout: 10000,
+};