test(rest): declare OS_REGISTRY_LOG in the vitest harness

`packages/rest` is the untouched CONTROL in
docs/audits/2026-09-test-log-volume-census.md: while PR #13985 and PR #14016
declared a registry log level in four harnesses, this suite got none, and the
audit measures 528 residual `[Registry]` lines here — eight times what declared
objectql still emits. Six test files in this package construct bare
`SchemaRegistry` instances, so the chatter is per registered item per case.

This declares the level in the harness only. objectql's shipped `'info'`
default is unchanged for every production reader, and no library code is made
aware of a test runner: `OS_REGISTRY_LOG` is the engine's own published seam
(`SchemaRegistryOptions.logLevel` / `REGISTRY_LOG_LEVELS`).

The ADR-0005 `[Registry] Collision` diagnostics ride a bare `console.warn` that
the level never gates, so a real shadowing still speaks here.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012zGPuVVX3deAx9LdjK8jCk

Author: claude

packages/rest/vitest.config.ts

@@ -12,6 +12,19 @@ export default defineConfig({
     // Mechanism + measured costs: examples/app-showcase/vitest.config.ts.
     // Enforced repo-wide by scripts/check-console-intercept-disarm.mjs.
     disableConsoleIntercept: true,
+    // #13517 / #15425: quiet the SchemaRegistry's per-item registration
+    // chatter — the engine's OWN `OS_REGISTRY_LOG` seam
+    // (`SchemaRegistryOptions.logLevel` / `REGISTRY_LOG_LEVELS`, objectql's
+    // registry.ts), not a change to its shipped 'info' default and not a
+    // library that sniffs `process.env.VITEST`. ⭐ This suite is the one
+    // `docs/audits/2026-09-test-log-volume-census.md` kept as its untouched
+    // CONTROL while #13985/#14016 quieted four others, and it measures 528
+    // residual `[Registry]` lines here — eight times what declared objectql
+    // still emits. Six test files in this package construct bare registries.
+    // The ADR-0005 `[Registry] Collision` diagnostics go through a bare
+    // `console.warn` the level never gates, so a real shadowing still speaks.
+    // Enforced by scripts/check-registry-log-declared.mjs.
+    env: { OS_REGISTRY_LOG: 'warn' },
     globals: true,
     environment: 'node',
   },