Update trunk.yaml: Rust and Ruby toolchain improvements

[dfrankland]

Summary

Stacked on #1112.

• Rust: Switch from hermetic nightly download to SYSTEM, with cargo-fmt/clippy using run_when: [cli] so they're skipped in CI (CI uses prepare-rs/action.yaml directly instead)
• Ruby: Switch from ruby-build (compiles from source, slow) to jdx/ruby pre-built binaries via the fake ruby-build wrapper added in Add fake ruby-build wrapper for jdx/ruby #1112; bumps Ruby 3.1.4 → 4.0.5
• rubocop: Bump 1.39.0 → 1.87.0 alongside the Ruby upgrade
• Everything else: Bump all linter/tool versions to latest

Test plan

• trunk tools install --verbose completes with no failures
• trunk check runs rubocop successfully on Ruby files
• Rust linters (clippy, cargo-fmt) work locally

🤖 Generated with Claude Code

[trunk-staging-io]

     

Failed Test	Failure Summary	Logs
variant_quarantine_test should be quarantined when run with variant	A test expected the sum of 2 + 2 to be 5, but it was actually 4, indicating a failing assertion.	Logs ↗︎

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.40%. Comparing base (9ed5b45) to head (58fb4c9).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1113      +/-   ##
==========================================
+ Coverage   82.14%   82.40%   +0.25%     
==========================================
  Files          69       69              
  Lines       15243    15243              
==========================================
+ Hits        12522    12561      +39     
+ Misses       2721     2682      -39     

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[trunk-io]

     

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[TylerJang27]

Noting the failing TS stuff

[trunk-io]

😎 Merged directly without going through the merge queue, as the queue was empty and the PR was up to date with the target branch - details.