feat(experimental): add printImportBreakdown.limit (fix: trim importDurations data)

[hi-ogawa]

Description

• Closes Reporters data is bloated compared to v3.1.x #9216
• Part of Enhance importBreakdown support #9141

(Largely 🤖 Generated with Claude Code)

Addresses the data size concern from #9141 and #9262. The importDurations metadata scales by O(test files × source files) but reporting only shows top N imports.

Summary

• Add experimental.printImportBreakdown: { enabled?: boolean, limit?: number } config

  • enabled (default: false): Enable import breakdown display in CLI
  • limit (default: 10): Number of imports to show in CLI output.
    • this also affect the heuristics to truncate importDurations
    • limit = 0: Opt-out from importDurations collection entirely

• Trim importDurations at worker level in getImportDurations():

  • Keep top Math.max(50, limit * 5) entries per test file so that UI breakdown can still do "show 10 + more".
  • Reduces IPC payload and main process memory (though I couldn't verify any meaningful impact in feat: ability to turn off import durations collection #9262)

TBD?

• This changes default importDurations collection available to be 50, which affects existing usage outside of base reporter. I think collecting all imports by default is largely unnecessary, so I think it's fine default.
• VSCode extension's collectModuleDurationsDiagnostic() accumulates times across test files. Trimmed long-tail modules may show incomplete totals. To preserve the previous behavior, extension can overwrite limit to Infinity?

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[sheremet-va]

I don't think this makes sense, to be honest. If there is a limit, then there is a limit. Maybe remove "show more" in UI

[sheremet-va]

Shouldn't it be 0 by default then

I think we can just say "enable this option to see import breakdown" in the current popup

[hi-ogawa]

Right, that works too. It looks like I was just over-complicating things.