PoC: Display Node-RED Dashboard inline in the editor

### Description

When a user builds a dashboard with the FlowFuse Expert, they should be able to see it update live — without leaving the editor.

Today, the dashboard opens in a separate browser tab. This breaks the iteration loop: talk to the expert, deploy, check the result, repeat. The user has to context-switch constantly.

### Expected Experience

The user opens the FlowFuse Expert and asks it to build an OEE dashboard. The expert creates the flow and dashboard nodes. The user clicks Deploy. The dashboard appears right there in the editor — next to the Expert panel, next to the canvas. The user says "change the line chart to a bar chart." The expert updates the nodes. The user deploys again. The dashboard refreshes. No tab switching, no hunting for URLs.

For users who only care about building dashboards and don't know Node-RED internals, the dashboard preview may matter more than the flow canvas itself.

### Constraints

- Users must click Deploy for changes to take effect (Node-RED platform limitation — this PoC works within it, not around it)
- PoC for internal validation — share internally before public release

### Related

- **FlowFuse/flowfuse#6267** — Immersive editor refactor with pinnable drawer (Serban's PoC). This defines the layout the dashboard panel must fit into.
- **FlowFuse/flowfuse#6749** — Inline actions between Expert and Node-RED
- **#174** — Deploy mode action support
- **#210** — MCP integration into AI BE agent

### References

- Discussed in "Sync on MCP/AI Andrea tickets" meeting (2026-03-30)

Start by reviewing related issues #6267, #6749, #174, and #210 to understand the editor layout, inline actions, deploy behavior, and integration context. Done means a deployed dashboard renders and refreshes inside the editor for internal validation, without requiring a separate browser tab.

Written by the indexing model from the issue text.