feat: add server helpers, make connect() to default to parent post transport (#165)

* feat: add server helpers and optional connect() transport

Add `src/server/` with convenience functions for registering MCP App tools
and resources:

- `registerAppTool(server, name, config, handler)`
- `registerAppResource(server, name, uri, config, callback)`

The `transport` parameter in `App.connect()` is now optional, defaulting to
`PostMessageTransport(window.parent)`.

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

Co-Authored-By: Claude <noreply@anthropic.com>

* Update src/server/index.ts

Co-authored-by: Jonathan Hefner <jonathan@hefner.pro>

* fix: refine server helper types

- Make RESOURCE_URI_META_KEY required in McpUiAppToolConfig (tools need a UI resource)
- Make _meta optional in McpUiAppResourceConfig (not all resources need custom metadata)

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

Co-Authored-By: Claude <noreply@anthropic.com>

* refactor: simplify RESOURCE_URI_META_KEY re-export

* refactor: consolidate export statements

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Jonathan Hefner <jonathan@hefner.pro>

package.json

@@ -23,6 +23,10 @@
       "types": "./dist/src/app-bridge.d.ts",
       "default": "./dist/src/app-bridge.js"
     },
+    "./server": {
+      "types": "./dist/src/server/index.d.ts",
+      "default": "./dist/src/server/index.js"
+    },
     "./schema.json": "./dist/src/generated/schema.json"
   },
   "files": [