Add "expert" module to product store

[cstns]

Description

adding the assistant vuex module boilerplate

Related Issue(s)

closes #6225

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 76.78%. Comparing base (b06203a) to head (6894821).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6226   +/-   ##
=======================================
  Coverage   76.78%   76.78%           
=======================================
  Files         384      384           
  Lines       19444    19444           
  Branches     4675     4675           
=======================================
  Hits        14931    14931           
  Misses       4513     4513           

Flag	Coverage Δ
backend	76.78% <ø> (ø)

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[Steve-Mcl]

all good but should we start referring to this as ff-expert (in code) to distinguish it from ff-assistant?

[cstns]

renamed it to simply expert for the sake of having a single named module not a composite one. It's under the product namespace so it makes sense conceptually