Fix Results tab Metric display names containing replacement syntax

[isuttell]

Summary

Gate check details on the Results tab rewrite raw Metric ids through withMetricNames. String.replaceAll treats $&, $', and $ in authored Metric display names as JavaScript replacement patterns, so a name like Revenue $& rendered as Revenue metric_x. This change treats the authored display name as literal text.

Changes

• Pass a replacer function to replaceAll so Metric display names are substituted byte-for-byte.
• Add a focused Control Panel helper test for $&, $', $, an ordinary display name, and the deleted-Metric id fallback.

Risk: LOW

• Areas touched: Control Panel Results Gate-check display helper only.
• Security: Display-only. Names remain React text, not markup.
• Performance: None.
• Breaking: None. Gate decisions, stats, Run state, and API payloads are unchanged.

Test plan

Issue-required checks on head 05a8225a483176d2ecd732cd3448ccadf46fd6fc:

• Focused Control Panel helper test: pnpm --filter @splitch/control-panel exec vitest run --config vitest.config.ts src/lib/experiments/metric-names.test.ts — 1 file / 7 tests passed (2026-09-16 17:24:15Z)
• Cache-busted CI graph (pnpm verify:ci --force equivalent): pnpm audit --audit-level=high && pnpm exec turbo run //#depcruise //#knip //#format:check //#spec:lint //#docs:lint //#check:cli-mcp-parity //#test:scripts lint typecheck test test:connect-snippet stats:golden stats:property build --force --concurrency=4 — 106/106 successful, 0 cached, 8m42s. Audit: no high/critical findings.

Supporting evidence:

• Hosted Verify on this head: SUCCESS (https://github.com/zaks-io/splitch/actions/runs/35127581221)
• @splitch/control-panel package tests: 163 files / 1400 passed
• verify:commit and verify:push passed before push

Issue: SPL-587

Linear Issue: SPL-587

  

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