test(spec): re-point object-metric icon citation to index.tsx:299 (#21808)

Fixes #21802

Clause-②: no

Before: `packages/spec/src/ui/component.test.ts:4146` cited
`plugin-dashboard/src/index.tsx:204` for the `object-metric` `icon`
input. At objectui `9dfaca6543` (the current `.objectui-sha`; same at
the old pin `2e818d0b51ec`) that line is a lone closing brace.
After: cites `index.tsx:299`, where the `object-metric` registration
(starts `:262`) declares `{ name: 'icon', type: 'string' }`.

Read evidence (read-only objectui clone at
`9dfaca654311cddd81714153c4f82c241d7cdc54`): `sed -n 204p` is a closing
brace; `:262` is the `'object-metric'` registration; `:299` is its icon
input. (`:192` is the sibling metric registration's icon, before
`:262`.)

Comment-only change in a test file; publishes nothing, no changeset.

Acceptance notes: other anchors in the same comment
(`ObjectMetricWidget.tsx:142`, `:474`, `MetricWidget.tsx:312-321`,
`:373-382`) do not match at this pin (e.g. `:142` is now docblock text);
they read as dated, not re-pointed here per scope.

Gates: `vitest run src/ui/component.test.ts` 367 passed;
`check:objectui-pin-citations --verify-anchors` OK; `check:nul-bytes`,
`check:cross-package-test-inputs`, `check:test-source-alias` OK.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

https://claude.ai/code/session_01VDtqoecgES7ScQYGbFVDRv

Co-authored-by: Claude <noreply@anthropic.com>

Author: objectstack-fleet[bot]

packages/spec/src/ui/component.test.ts

@@ -4143,7 +4143,7 @@ describe('ObjectMetricPropsSchema icon liveness (#10053)', () => {
   const metric = ComponentPropsMap['object-metric'];
 
   it('accepts an icon on the metric tile — the value objectui resolves via getLazyIcon', () => {
-    // objectui `plugin-dashboard/src/index.tsx:204` publishes the input
+    // objectui `plugin-dashboard/src/index.tsx:299` publishes the input
     // (this read `:161` until the `a472b0716` re-measure: wrong since written,
     // not shifted — that line is a sentence in the registry shell's docblock,
     // not the `object-metric` registration's `icon` input, and the file is