bench: monitor config loading performance in CI

[fengmk2]

Repeated vite.config.* loading can slow vp check --fix and vp staged.

Add a benchmark for root and package commands. Record timings and config evaluation counts separately. Show baseline and current median and p95 values, plus absolute and percentage changes.

CI runs only on relevant PR updates. It compares compatible results from the stack's base branch or earlier runs of the same PR. Post or update a PR comment when any median changes by more than ±5%. Fork PRs retain the report in the job summary.

A timing failure requires more than 20% and 40 ms median growth, with the current lower quartile above the previous upper quartile. Excess config evaluations also fail CI.

Related to #2698.

[cloudflare-workers-and-pages]

🚀 Deploying Preview to Cloudflare 🚀

Preview URL: https://bench-config-performance-viteplus-dev.voidzero-docs.workers.dev (commit a07ad93)

This URL reflects your latest Preview deployment

Preview Deployments by commit

Status	Deployment URL	Commit	Updated (UTC)	See this deployment's details
Build: Success ✅ Deployment: Success ✅ View logs ↗	https://60dc1583-viteplus-dev.voidzero-docs.workers.dev	a07ad93	2026-09-22T09:27:29.836Z	Visit the dashboard ↗
Build: Success ✅ Deployment: Success ✅ View logs ↗	https://bd383977-viteplus-dev.voidzero-docs.workers.dev	0dc5ad3	2026-09-22T08:05:53.074Z	Visit the dashboard ↗
Build: Success ✅ Deployment: Success ✅ View logs ↗	https://1688a2e3-viteplus-dev.voidzero-docs.workers.dev	e031327	2026-09-22T07:58:08.326Z	Visit the dashboard ↗
Build: Success ✅ Deployment: Success ✅ View logs ↗	https://f3c6c3c4-viteplus-dev.voidzero-docs.workers.dev	386dde6	2026-09-22T07:54:37.218Z	Visit the dashboard ↗

[github-actions]

Benchmark run for PR head a07ad93b9c076c0470d7c7fb616fe2ac84ec8a9c.

9 case(s) changed by more than ±5% in median time. Negative changes are faster; positive changes are slower.

Config performance

Baseline revision: 5bab3cf10565cfd983993348f67e05a1d5abf282.

Current revision: e20b61816c2b3f8ec673436879abf85987a02574. Node v22.18.0; linux/x64; AMD EPYC.

Case	Median (ms), baseline → current	p95 (ms), baseline → current	Median change	Config evaluations (current, separate probe)
root/check/no-config	280.5 → 302.9	304.6 → 314.9	+22.4 ms (+8.0%)	0
root/check/minimal	484.4 → 524.8	491.4 → 547.9	+40.4 ms (+8.3%)	check: 1, oxfmt: 1, oxlint: 1, oxfmt: 1
root/check/defineConfig	491.5 → 530.6	505.0 → 547.0	+39.1 ms (+8.0%)	check: 1, oxfmt: 1, oxlint: 1, oxfmt: 1
package/check/minimal	503.4 → 538.2	510.6 → 561.1	+34.8 ms (+6.9%)	check: 4, oxfmt: 1, oxlint: 1, oxfmt: 1
package/check/blocks	497.0 → 535.2	506.9 → 571.0	+38.2 ms (+7.7%)	check: 4, oxfmt: 1, oxlint: 1, oxfmt: 1
root/fmt/minimal	222.2 → 238.0	226.9 → 258.8	+15.8 ms (+7.1%)	oxfmt: 1
root/lint/minimal	189.2 → 202.9	206.2 → 223.9	+13.6 ms (+7.2%)	oxlint: 1
root/staged/minimal	625.8 → 673.5	652.8 → 732.6	+47.8 ms (+7.6%)	staged: 1, check: 1, oxfmt: 1, oxlint: 1, oxfmt: 1
root/staged/noop	151.1 → 168.8	164.7 → 185.2	+17.7 ms (+11.7%)	staged: 1

Fresh processes, warm filesystem and Node compile caches. Config logging is disabled during timing.
A timing regression requires >20% and >40 ms median growth, with current p25 above baseline p75.