Chore/bump open aea 2.1.0 & open autonomy 0.21.12

[DavidMinarsch]

Proposed changes

Summary

• Bump open-aea dependency from 2.1.0rc6 to 2.1.0 across all config files (38 files)
• Bump open-autonomy version from 0.21.12rc5 to 0.21.12 across all config files (22 files)
• Set release date for v0.21.12 to 2026-03-08 in HISTORY.md
• Add open-aea bump to upgrading docs
• Add .claude/ to .gitignore

Test plan

• Verify all linters pass
• Verify autonomy packages lock --check passes
• Verify test_abstract_round_abci_skill_hash test passes
• Verify doc IPFS hashes are up to date

Types of changes

What types of changes does your code introduce? (A breaking change is a fix or feature that would cause existing functionality and APIs to not work as expected.)
Put an x in the box that applies

• Non-breaking fix (non-breaking change which fixes an issue)
• Breaking fix (breaking change which fixes an issue)
• Non-breaking feature (non-breaking change which adds functionality)
• Breaking feature (breaking change which adds functionality)
• Refactor (non-breaking change which changes implementation)
• Messy (mixture of the above - requires explanation!)

Checklist

Put an x in the boxes that apply.

• I have read the CONTRIBUTING doc
• I am making a pull request against the main branch (left side). Also you should start your branch off our main.
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have locally run AI agents that could be impacted and they do not present failures derived from my changes
• Public-facing documentation has been updated with the changes affected by this PR. Even if the provided contents are not in their final form, all significant information must be included.
• Any backwards-incompatible/breaking change has been clearly documented in the upgrading document.

Further comments

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.40%. Comparing base (69a29c2) to head (2aef8fa).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2441   +/-   ##
=======================================
  Coverage   92.40%   92.40%           
=======================================
  Files         229      229           
  Lines       16832    16832           
=======================================
+ Hits        15553    15554    +1     
+ Misses       1279     1278    -1     

Flag	Coverage Δ
unittests	92.40% <100.00%> (+<0.01%)	⬆️

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