feat: green-by-skip census — skip counts in the classifier, all-skipped labeling in the paid runner

bun's 'Ran N tests' line COUNTS skipped tests, so a codex/gemini shard
whose every test self-skipped (binary absent on the runner — true of every
CI runner today) exits 0, dodges the hollow-shard guard, and reads as
coverage in the weekly census. The classifier now parses bun's ' N skip' /
' N pass' recap lines; ShardOutcome carries skippedTests; formatSummary and
the fail-closed slices report label an all-skipped pass explicitly:
'all N tests SKIPPED — verified nothing'. Status stays 'passed' (external
service availability is host state, not a repo regression) but the census
can no longer mistake absence for coverage.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

test/strict-output.test.ts

@@ -89,6 +89,38 @@ describe('BunTestOutputClassifier', () => {
     expect(summary.terminalFileCounts).toEqual([2]);
     expect(strictTestExitCode(0, summary, 2)).toBe(0);
   });
+
+  // "Ran N tests" COUNTS skipped tests, so the skip/pass count lines are the
+  // only stream evidence separating verified work from green-by-skip (a
+  // codex/gemini file whose every test self-skips on a binary-less runner).
+  it('parses the skip and pass count lines from bun’s recap block', () => {
+    const c = new BunTestOutputClassifier();
+    c.write(' 1 pass\n 2 skip\n 0 fail\nRan 3 tests across 1 file. [7.00ms]\n');
+    const summary = c.end();
+    expect(summary.passedTests).toBe(1);
+    expect(summary.skippedTests).toBe(2);
+    expect(summary.terminalTestCounts).toEqual([3]);
+    // all-skipped is still exit-0 at the classifier layer — the census
+    // labeling happens in the paid runner, not here
+    expect(strictTestExitCode(0, summary, 1)).toBe(0);
+  });
+
+  it('skip/pass counts survive ANSI color and chunk shears', () => {
+    const c = new BunTestOutputClassifier();
+    c.write(' 4 pa');
+    c.write('ss\n 9 skip\n');
+    const summary = c.end();
+    expect(summary.passedTests).toBe(4);
+    expect(summary.skippedTests).toBe(9);
+  });
+
+  it('prose mentioning skip counts does not pollute the tally', () => {
+    const c = new BunTestOutputClassifier();
+    c.write('console.log said: 7 skip is what we expect later\n');
+    c.write('(fail) 3 skip handling [1.00ms]\n');
+    const summary = c.end();
+    expect(summary.skippedTests).toBe(0);
+  });
 });
 
 describe('installChildSignalForwarding — cancellation terminates the RUN', () => {