refactor: convert custom-provider example to package with deps

- Move custom-provider.ts to custom-provider/index.ts
- Add package.json with @anthropic-ai/sdk dependency
- Extension now requires npm install before use

packages/coding-agent/examples/extensions/custom-provider/.gitignore

@@ -0,0 +1 @@
+node_modules/

packages/coding-agent/examples/extensions/custom-provider/index.ts

@@ -9,11 +9,14 @@
  * - Two model definitions
  *
  * Usage:
+ *   # First install dependencies
+ *   cd packages/coding-agent/examples/extensions/custom-provider && npm install
+ *
  *   # With OAuth (run /login custom-anthropic first)
- *   pi -e ./custom-provider.ts
+ *   pi -e ./packages/coding-agent/examples/extensions/custom-provider
  *
  *   # With API key
- *   CUSTOM_ANTHROPIC_API_KEY=sk-ant-... pi -e ./custom-provider.ts
+ *   CUSTOM_ANTHROPIC_API_KEY=sk-ant-... pi -e ./packages/coding-agent/examples/extensions/custom-provider
  *
  * Then use /model to select custom-anthropic/claude-sonnet-4-5
  */

packages/coding-agent/examples/extensions/custom-provider/package-lock.json

@@ -0,0 +1,24 @@
+{
+  "name": "pi-extension-custom-provider",
+  "version": "1.0.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "pi-extension-custom-provider",
+      "version": "1.0.0",
+      "dependencies": {
+        "@anthropic-ai/sdk": "^0.52.0"
+      }
+    },
+    "node_modules/@anthropic-ai/sdk": {
+      "version": "0.52.0",
+      "resolved": "https://registry.npmjs.org/@anthropic-ai/sdk/-/sdk-0.52.0.tgz",
+      "integrity": "sha512-d4c+fg+xy9e46c8+YnrrgIQR45CZlAi7PwdzIfDXDM6ACxEZli1/fxhURsq30ZpMZy6LvSkr41jGq5aF5TD7rQ==",
+      "license": "MIT",
+      "bin": {
+        "anthropic-ai-sdk": "bin/cli"
+      }
+    }
+  }
+}

packages/coding-agent/examples/extensions/custom-provider/package.json

@@ -0,0 +1,19 @@
+{
+  "name": "pi-extension-custom-provider",
+  "private": true,
+  "version": "1.0.0",
+  "type": "module",
+  "scripts": {
+    "clean": "echo 'nothing to clean'",
+    "build": "echo 'nothing to build'",
+    "check": "echo 'nothing to check'"
+  },
+  "pi": {
+    "extensions": [
+      "./index.ts"
+    ]
+  },
+  "dependencies": {
+    "@anthropic-ai/sdk": "^0.52.0"
+  }
+}