[Remote rendering 4.3] RemoteCanvas frame display and interaction forwarding

### 📝 Description of the feature

This is the first real remote frontend work. Everything before this was backend or the mode probe.

Create a `RemoteCanvas` to subscribe to the frame stream from 4.1, and draws frames to a canvas, forwarding mouse and wheel events back to the server, built from scratch against the wslink protocol since trame-rca ships only a Vue component.

`RemoteRenderer.ts` implements `IRenderer` over trigger calls to the server.

### Acceptance Criteria

A fresh frame appears on connect and reconnect (no blank canvas).
Tests pass

### 💵 Business Value

_No response_

### 🔗 Useful links and references

_No response_

Start with RemoteRenderer.ts and the frame stream from 4.1, then review the wslink protocol and the existing trame-rca Vue component for relevant behavior. Verify the RemoteCanvas draws a fresh frame on connect and reconnect, forwards mouse and wheel events to the server, and that the tests pass.

由索引模型根据 Issue 内容生成。