test(mosaic): pin quickstart.md to status: active, the contract's value for in-force

CI 2592 proved the old front-matter schema HAD a consumer. vision's C2 concluded "no consumer
found", fred's decision A rested on "no installed base to protect", and I accepted both. All three
of us were wrong.

installation-documentation.spec.ts:39 asserted a raw regex over the markdown text:

    expect(markdown).toMatch(/^---\n[\s\S]*?\nstatus: current\n[\s\S]*?\n---\n/);

Not a front-matter parse and not a key lookup, which is why a search organised around parsing
primitives could not see it. Stamping docs/USER-GUIDE/getting-started/quickstart.md replaced
`status: current` with `status: active` and turned it red.

Updated to the contract's vocabulary, intent unchanged: the page must still declare itself in
force, and must still teach no curl-pipe-to-shell install. Verified by evaluating both regexes
against the real file: old false, new true. Control: a page carrying `superseded-by` still fails
the new regex, so the assertion still asserts something.

2592 also confirms the NORTH_STAR revert took: the north-star drift test is green, `format` and
`lint` are green, and this was the only failure in 1617 tests.

Method point worth keeping: the full suite is a stronger consumer search than any grep, because it
does not depend on guessing how a consumer reads the file.

docs/plans/2026-08-20_w4-document-contract-worklist.md

@@ -324,3 +324,31 @@ contract". The reason this is not applied unilaterally: it decides which documen
 other when `docs/README.md` and `docs/plans/2026-08-20_stack-docs-flatten-and-alignment.md` disagree
 about the contract, and they already differ (the plan's enum has 7 values, the README's now has 6).
 That is an authority question, not a classification one.
+
+## The old schema DID have a consumer, and CI found it
+
+vision's C2 concluded "no consumer found" after searching by parsing primitive rather than by key
+name. fred's decision A rested on "no installed base to protect." I accepted both. **All three of
+us were wrong, and the full test suite is what proved it.**
+
+`packages/mosaic/src/installation-documentation.spec.ts:39` asserted:
+
+```ts
+expect(markdown).toMatch(/^---\n[\s\S]*?\nstatus: current\n[\s\S]*?\n---\n/);
+```
+
+That is a raw regex over the markdown text, not a front-matter parse and not a key lookup, which is
+exactly why a search organised around parsing primitives could not see it. It pins
+`docs/USER-GUIDE/getting-started/quickstart.md` to the old vocabulary. Replacing `status: current`
+with `status: active` turned it red.
+
+Updated to `status: active`, the contract's value for "in force", with the reason in a comment
+beside it. Verified by evaluating both regexes against the real file: old `false`, new `true`.
+Control: a page carrying `superseded-by` still fails the new regex, so the assertion still asserts
+something rather than matching anything with front matter.
+
+**The method point, which outlives this file.** CI 2592 ran 1617 tests against the stamped tree: 1
+failed, 1616 passed. That is a stronger consumer search than any grep the three of us ran, because
+it does not depend on guessing how a consumer reads the file. **Run the suite before concluding a
+documentation change has no code consumers.** Two independent seats and a reviewer searching by
+hand missed the one that existed.