docs: add ai.enabled platform configuration and team type feature

[cstns]

Description

Updates documentation to reflect the new ai platform feature flag introduced in #7317.

Related Issue(s)

closes #7322
part of #7310

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 76.61%. Comparing base (93900f4) to head (69b9f17).

Additional details and impacted files

@@                               Coverage Diff                                @@
##           generic-ai-platform-and-team-level-feature-flag    #7321   +/-   ##
================================================================================
  Coverage                                            76.61%   76.61%           
================================================================================
  Files                                                  405      405           
  Lines                                                20603    20603           
  Branches                                              4987     4987           
================================================================================
  Hits                                                 15785    15785           
  Misses                                                4818     4818           

Flag	Coverage Δ
backend	76.61% <ø> (ø)

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