docs(upstream): record the v0.53.1 release

[sunerpy]

Summary

The release record for v0.53.1, as for every release since v0.51.0.

• Current alignment: "Shipped in v0.53.1" (fix(resolve): keep Rust method calls that lost their receiver off functions and std names #307, the four KEEP-RUST receiver gates, extraction version 21) replaces the "on main, not yet released" note.
• Sync log: a dated v0.53.1 RELEASED entry:
  • release PR chore: release 0.53.1 #308 merged as 4a6c21b, with the tag at that commit;
  • fix(resolve): keep Rust method calls that lost their receiver off functions and std names #307 squashed as f9f96c3 from its reviewed head ec1bf0f;
  • release run 37104659922, twelve jobs on the first attempt, over main CI 37104659935;
  • the publish time and the linux-musl digest;
  • the black-box acceptance of the downloaded release against v0.53.0 (/tmp/verify-0.53.1.sh, log /tmp/evidence-p15/verify-0.53.1.log): checksums and attestations for all six archives, the four rules old vs new, and the 20 → 21 upgrade.

Dated entries are untouched; the only lines replaced are the Current alignment note.

Verification

make fmt-check and make docs-check pass. There is no code change.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@            Coverage Diff             @@
##             main     #309      +/-   ##
==========================================
- Coverage   95.07%   95.07%   -0.01%     
==========================================
  Files         198      198              
  Lines      108998   108998              
==========================================
- Hits       103634   103631       -3     
- Misses       5364     5367       +3     

see 1 file with indirect coverage changes

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