feat: remove at-block in 3.4

[francesco-stacks]

Description

Implementation of SIP proposal: stacksgov/sips#262

• disable at-block in clarity1-4, both at deploy-time for new contracts, and at runtime for contracts already deployed.
• remove at-block completely in clarity5+.
• adjusts tests using at-block.

Applicable issues

• fixes #

Additional info (benefits, drawbacks, caveats)

Checklist

• Test coverage for new or modified code paths
• For new Clarity features or consensus changes, add property tests (see docs/property-testing.md)
• Changelog is updated
• Required documentation changes (e.g., rpc/openapi.yaml for RPC endpoints, event-dispatcher.md for new events)
• New clarity functions have corresponding PR in clarity-benchmarking repo

[brice-stacks]

This looks good to me. Can you just update clarity/src/vm/docs/mod.rs with the change that at-block is no longer supported after epoch 3.4?

[francesco-stacks]

This looks good to me. Can you just update clarity/src/vm/docs/mod.rs with the change that at-block is no longer supported after epoch 3.4?

added in 399daf9

[brice-stacks]

lgtm!

[jcnelson]

LGTM; just one question.

[aaronb-stacks]

LGTM!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 64.36%. Comparing base (56a1a1e) to head (b4dd046).
⚠️ Report is 14 commits behind head on develop.

❌ Your project status has failed because the head coverage (64.36%) is below the adjusted base coverage (73.38%). You can increase the head coverage or adjust the Removed Code Behavior.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #6937      +/-   ##
===========================================
- Coverage    73.38%   64.36%   -9.02%     
===========================================
  Files          412      412              
  Lines       219352   219362      +10     
  Branches       338      338              
===========================================
- Hits        160976   141201   -19775     
- Misses       58376    78161   +19785     

Files with missing lines	Coverage Δ
clarity-types/src/errors/analysis.rs	73.66% <100.00%> (+2.74%)	⬆️
...y/src/vm/analysis/type_checker/v2_1/natives/mod.rs	85.16% <100.00%> (-1.55%)	⬇️
clarity/src/vm/docs/mod.rs	6.12% <ø> (-71.32%)	⬇️
clarity/src/vm/functions/database.rs	87.11% <100.00%> (-1.50%)	⬇️
clarity/src/vm/functions/mod.rs	96.93% <ø> (+1.02%)	⬆️
stacks-common/src/types/mod.rs	77.18% <100.00%> (-0.58%)	⬇️

... and 270 files with indirect coverage changes

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