test: suppress console output noise in vitest

Add onConsoleLog: () => false to vitest config to silence expected
warn/error calls from production code when tests deliberately feed bad
input (e.g. parseJson with malformed JSON). Tests can still use
vi.spyOn(console, ...) to assert on console calls explicitly.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/vitest.config.ts

@@ -18,5 +18,11 @@ export default defineConfig({
       resolve(__dirname, 'unit/**/*.test.ts'),
       resolve(__dirname, 'integration/**/*.test.ts'),
     ],
+    // Suppress console output from production code during tests (e.g. expected
+    // warn/error calls when intentionally feeding bad input to parsers).
+    // Tests that need to assert on console calls can still use vi.spyOn(console, ...).
+    onConsoleLog() {
+      return false;
+    },
   },
 });