[cargo-nextest] add a store export-chrome-trace command

[sunshowers]

Export data in the Chrome event trace format, suitable for importing into Perfetto and other viewers.

[Copilot]

Pull request overview

Adds a new cargo nextest store export-chrome-trace subcommand that converts recorded run events into Chrome Trace Event Format JSON for visualization in Perfetto / chrome://tracing, plus supporting runner-side conversion logic and snapshot tests.

Changes:

• Introduce nextest-runner::record::convert_to_chrome_trace with grouping + JSON formatting options.
• Wire up cargo nextest store export-chrome-trace (including CLI parsing, archive/store support, and error/exit-code mapping).
• Add snapshot and unit tests validating emitted trace structure (pause/resume gaps, retries/flows, counters, etc.).

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
nextest-runner/src/record/chrome_trace.rs	New converter from recorded events → Chrome trace JSON, with extensive tests.
nextest-runner/src/record/mod.rs	Add module + re-export converter API/types.
nextest-runner/src/record/display.rs	Factor run-id prefix highlighting into shared Styles helpers.
nextest-runner/src/record/AGENTS.md	Document Chrome trace export behavior and invariants.
nextest-runner/src/errors.rs	Add ChromeTraceError error type.
cargo-nextest/src/dispatch/utility/store.rs	Add store export-chrome-trace subcommand implementation + CLI options.
cargo-nextest/src/errors.rs	Map Chrome trace export errors to ExpectedError + exit codes.
cargo-nextest/src/dispatch/core/tests.rs	Add CLI argument parsing coverage for new subcommand/options.
nextest-runner/src/record/snapshots/*.snap	Add insta snapshots for trace output (basic/pause-resume/slot-mode).

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[codecov]

Codecov Report

❌ Patch coverage is 23.38710% with 95 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.12%. Comparing base (8966706) to head (8a1b20d).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
cargo-nextest/src/dispatch/utility/store.rs	1.12%	88 Missing ⚠️
cargo-nextest/src/errors.rs	0.00%	5 Missing ⚠️
nextest-runner/src/record/display.rs	93.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3163      +/-   ##
==========================================
+ Coverage   84.62%   85.12%   +0.49%     
==========================================
  Files         156      157       +1     
  Lines       43838    46067    +2229     
==========================================
+ Hits        37100    39214    +2114     
- Misses       6738     6853     +115     

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