feat(sdk): emit CASE_MISMATCH reason for non-canonical pass casing (#3184)

Cycle 10 of ~15: a captured 'result:' value that lowercases to
'pass' but isn't literally 'pass' now produces a CASE_MISMATCH
reason rather than a generic NON_PASS_RESULT — so operators can
distinguish a real non-pass from a likely typo.

sdk/src/query/phase-uat-passed.test.ts

@@ -272,4 +272,34 @@ expected: thing
       await rm(localTmp, { recursive: true, force: true });
     }
   });
+
+  it("emits CASE_MISMATCH reason when result value is \"PASS\" (uppercase variant of pass)", async () => {
+    const localTmp = await mkdtemp(join(tmpdir(), 'gsd-uat-c10-'));
+    try {
+      const phaseDir = join(localTmp, '.planning', 'phases', '05-case-mismatch');
+      await mkdir(phaseDir, { recursive: true });
+      const content = `---
+status: complete
+phase: 5
+source: roadmap
+started: 2026-05-18T00:00:00Z
+updated: 2026-05-18T00:00:00Z
+---
+
+### 1. Uppercase pass item
+expected: thing happens
+result: PASS
+`;
+      await writeFile(join(phaseDir, '05-HUMAN-UAT.md'), content);
+
+      const result = await isPhaseUatPassed(localTmp, '5');
+      expect(result.passed).toBe(false);
+      expect(result.items.length).toBe(1);
+      expect(result.reasons.length).toBe(1);
+      expect(result.reasons[0].code).toBe(REASON_CODE.CASE_MISMATCH);
+      expect(result.reasons[0].capturedValue).toBe('PASS');
+    } finally {
+      await rm(localTmp, { recursive: true, force: true });
+    }
+  });
 });