docs(hr-benchmarking): add profile viewing and off-CPU guidance

[bompus]

Adds commands and interpretation limits for local profile viewing, mixed native/JavaScript CPU attribution, allocation tracing and off-CPU analysis to the existing benchmarking tool reference. The additions come from a completed diagnostic trial; no benchmark improvement is claimed.

The reference now names speedscope, preserves default perf-script formatting for import, describes perf report --no-inline, explains heaptrack overhead, and pairs oha latency correction with its required rate limit. No tool becomes a benchmark prerequisite.

Validation on 5e97936: Node suite 151 pass / 7 skip; Bun suite 488 pass / 8 skip; skill scripts 338 pass; npm package check passed (235 files); pinned formatter passed. Pinned oxlint exited 0 with the existing no-control-regex warning in test/install-ps1.test.mjs. A real local speedscope import and scheduler-tracing smoke run also passed.

Review correction: the profileURL hash value is now encoded with encodeURIComponent, preserving nested query parameters. Confirmed in the packaged parser and a browser import with two query parameters. Focused formatting, privacy and local-link checks passed after the wording correction; no manual follow-up review was requested.

Summary by CodeRabbit

• Documentation
  • Updated benchmarking guidance for viewing Node.js and native CPU profiles in speedscope, retaining native symbols, and limiting inline frames in perf.
  • Added notes on heaptrack overhead and the limits of off-CPU tracing, including scheduler traces for measuring off-CPU time.
  • Clarified that oha latency correction requires fixed-rate mode (-q) to take effect.

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ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: Repository YAML (base), Organization UI (inherited)
• Review profile: CHILL
• Plan: Advanced
• Run ID: f83a642d-9897-428a-9ab2-fdeebfa618c9

📥 Commits

Reviewing files that changed from the base of the PR and between eb30674 and 44fc247.

📒 Files selected for processing: 2

• CHANGELOG.md
• skills/hr-benchmarking/references/tools.md

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📝 Walkthrough

The benchmarking reference clarifies when oha applies latency correction and adds instructions for profiling Rust and Node.js workloads. The Unreleased changelog records these documentation updates.

Changes: HR benchmarking guidance

Layer / File(s)	Summary
Update benchmarking instructions skills/hr-benchmarking/references/tools.md, CHANGELOG.md	The reference clarifies that oha requires -q for --latency-correction. It adds guidance on native and Node.js profiling, speedscope, heaptrack overhead, and scheduler tracing. The changelog records these updates.

Priority: ⬇️ Low

Merge Risk: ⚪ Minimal · up to 44fc2

This PR updates benchmarking and profiling guidance without changing runtime behavior. No actionable issue is established by the reviewed changes, so it is mergeable with normal checks.

### Architecture Summary

Architecture risk: 🔵 Low · up to 44fc2

The change affects 2 systems.

Changed systems: CHANGELOG.md, skills

Architecture concerns
No architecture-level concerns identified.

Review details

Systems and components

• observed — CHANGELOG.md (service) was modified; 1 changed file maps to changed impact.
• observed — skills (service) was modified; 1 changed file maps to changed impact.

Before / after behavior

• observed — Modified behavior in CHANGELOG.md: Adds an Unreleased hr-benchmarking changelog entry covering local speedscope profile viewing, native and JavaScript CPU attribution, the perf report --no-inline workaround, heaptrack overhead, off-CPU tracing limits, and oha’s --latency-correction and required -q rate limit.
• observed — Modified behavior in skills/hr-benchmarking/references/tools.md: The oha guidance now specifies that --latency-correction corrects coordinated omission for fixed-rate load and is ignored unless -q is set, replacing the statement that latency correction requires rate limiting.
• observed — Modified behavior in skills/hr-benchmarking/references/tools.md: Added profiling guidance for preserving native symbols in Rust release builds, exposing Node JIT frames to perf, retaining worker-thread CPU profiles, and using perf report --stdio --no-inline with its attribution limit recorded. Added speedscope viewing and import instructions, including checks for expected threads and stacks and local handling of private profiles. Added limits for heaptrack overhead and instructions for separate scheduler tracing when wall time exceeds CPU time, including attribution and tracepoint caveats.

Pre-merge checks: 6

Passed checks: 6 passed

Check name	Status	Explanation
Title check		The title clearly identifies the documentation change and names the main topics: profile viewing and off-CPU guidance.
Description check		The description explains what changed and why, reports validation results, confirms the Unreleased changelog entry, and addresses privacy and prerequisite constraints. It does not reproduce the templa…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Suppressions Explained		The pull request changes only CHANGELOG.md and skills/hr-benchmarking/references/tools.md. The added lines contain no lint, type-check, or formatter suppression directives, and no lint or formatte…
Rule Changes Documented		The pull request changes only CHANGELOG.md and skills/hr-benchmarking/references/tools.md. It does not change rules/core.md, rules/modifiers/*, or any skills/*/SKILL.md. The Unreleased sec…

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All reported issues were addressed across 2 files

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