Add default expert URLs

[hardillb]

fixes #6895

Description

Adds default URLs for assistant and expert using the new unified hostname expert.flowfuse.com.

NOT TO BE MERGED BEFORE: https://github.com/FlowFuse/CloudProject/pull/1224

Related Issue(s)

#6895

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

❌ Patch coverage is 66.66667% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.29%. Comparing base (c8c9ce5) to head (e01799c).
⚠️ Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
forge/config/index.js	66.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6949      +/-   ##
==========================================
- Coverage   76.29%   76.29%   -0.01%     
==========================================
  Files         403      403              
  Lines       20296    20302       +6     
  Branches     4881     4885       +4     
==========================================
+ Hits        15485    15489       +4     
- Misses       4811     4813       +2     

Flag	Coverage Δ
backend	76.29% <66.66%> (-0.01%)	⬇️

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[hardillb]

@Steve-Mcl I've had to remove 2 tests as there won't be a case of the URLs not being set anymore.

Hopefully this is just temporary until https://github.com/FlowFuse/engineering/issues/6 is fixed, when suitable new tests can be added.

[Steve-Mcl]

Should we not put the defaults in config/index.js so they are in one place and not repeated - or is there a subtlety i am missing?

Something like:

        if (config.assistant?.enabled === true && !config.assistant.service?.url) {
            config.assistant.service.url = 'https://expert.flowfuse/v1/openai'
        }
        if (config.expert?.enabled === true && !config.expert.service?.url) {
            config.expert.service.url = 'https://expert.flowfuse/v4/expert'
        }

[Steve-Mcl]

LGTM