Alter the expert's chat input

[cstns]

Description

Integrates Selected Flows into the chat prompt context and refactors the chat input UI for better utility and future extensibility.

• Selected flows are now injected into the chat prompt.
• New "Context Tray": Created a dedicated space at the bottom of the textarea for selection pills and action buttons.
• UX Alignment: Moved the Send/Stop button into the tray to follow standard UI patterns.
• Compact Design: Reduced button paddings for a more utilitarian feel.
• Resizable Input: Added horizontal resizing to the chat textarea.

The new layout de-congests the input field and creates a scalable container for upcoming UI elements like Agent selectors, File attachments, and Custom Prompt buttons.

expert-selection.mp4

Related Issue(s)

closes #6563

Checklist

• I have read the contribution guidelines
• Suitable unit/system level tests have been added and they pass
• Documentation has been updated
  • Upgrade instructions
  • Configuration details
  • Concepts
• Changes flowforge.yml?
  • Issue/PR raised on FlowFuse/helm to update ConfigMap Template
  • Issue/PR raised on FlowFuse/CloudProject to update values for Staging/Production
• Link to Changelog Entry PR, or note why one is not needed.

Labels

• Includes a DB migration? -> add the area:migration label

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.66%. Comparing base (7b033e1) to head (000aa64).
⚠️ Report is 19 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6581   +/-   ##
=======================================
  Coverage   76.66%   76.66%           
=======================================
  Files         398      398           
  Lines       20103    20103           
  Branches     4841     4841           
=======================================
  Hits        15411    15411           
  Misses       4692     4692           

Flag	Coverage Δ
backend	76.66% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[Steve-Mcl]

@cstns FYI - e2e test fail ✖ brokers/3rd-party-broker.spec.js again
re-running

[Steve-Mcl]

Approving with the agreement a follow up to better present results from the flow analysis - currently, it piggybacks the chat output and loops any issues or suggestions into a bullet list

[Steve-Mcl]

Approving with the agreement a follow up to better present results from the flow analysis - currently, it piggybacks the chat output and loops any issues or suggestions into a bullet list