[Remote rendering 4.2] Mode selection and remote entrypoint

### 📝 Description of the feature

Allow VISOR to start in either LOCAL (default) or REMOTE mode.

Backend entrypoint allowing selection of RenderingMode is already in place from 1.3 (wired to a remote stub). This builds the frontend equivalent for the first time.

On mount, the app opens a probe connection to the Trame server, reads which mode it's in and branches: for remote it keeps that connection open and hands it to the remote path rather than reopening one, for local it closes the probe and lets the local path take over. Remote mode must not initialize or download the wasm binary. Both modes serve from the same bundle.

### Acceptance Criteria

Remote mode downloads no wasm binary (no .wasm request in the network tab).
Tests pass

### 💵 Business Value

_No response_

### 🔗 Useful links and references

_No response_

从应用挂载点和现有的 RenderingMode 后端入口点开始，然后跟踪 Trame probe 连接、远程交接和本地 wasm 初始化。运行项目测试并验证远程模式会保持 probe 连接，而本地模式会关闭该连接，并且远程模式不会发出 .wasm 请求。

由索引模型根据 Issue 内容生成。