chore(opencode-sandbox): add SSH config, git safe directory, and test setup

.opencode-sandbox/tsconfig.json

@@ -0,0 +1,15 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "module": "commonjs",
+    "lib": ["ES2020"],
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "resolveJsonModule": true,
+    "types": ["node", "jest"]
+  },
+  "include": ["tests/**/*"],
+  "exclude": ["node_modules"]
+}