fix(expert): content ingestion after sso/mfa auth

[cstns]

Description

slight refactor of context ingestion on the flowfuse side to allow proper context ingestion independently of the auth method used: sso, mfa, email/pass

Related Issue(s)

closes https://github.com/FlowFuse/flowfuse/issues/6274

Checklist

• [x] 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[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 76.77%. Comparing base (2ffc036) to head (e4687df). :warning: Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6296   +/-   ##
=======================================
  Coverage   76.77%   76.77%           
=======================================
  Files         386      386           
  Lines       19527    19527           
  Branches     4694     4694           
=======================================
  Hits        14992    14992           
  Misses       4535     4535           

Flag	Coverage Δ
backend	76.77% <ø> (ø)

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