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 Control: a page carrying `superseded-by` still fails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.

packages/mosaic/src/installation-documentation.spec.ts

@@ -36,7 +36,9 @@ describe('current installation documentation safety', (): void => {
     async (relativePath): Promise<void> => {
       const markdown = await readFile(resolve(repositoryRoot, relativePath), 'utf8');
 
-      expect(markdown).toMatch(/^---\n[\s\S]*?\nstatus: current\n[\s\S]*?\n---\n/);
+      // `status: active` is the document contract's value for "in force"; it replaced the
+      // old `status: current` when the contract in docs/README.md became the single schema.
+      expect(markdown).toMatch(/^---\n[\s\S]*?\nstatus: active\n[\s\S]*?\n---\n/);
       expect(unsafeRemoteExecutionFindings(markdown)).toEqual([]);
     },
   );