ci: make Codecov patch coverage informational (Comfy-Org#13768)

## Summary

Make Codecov patch coverage informational so the critical Vitest
thresholds remain the coverage merge gate.

## Changes

- **What**: Configure the default `codecov/patch` status as
informational. Patch coverage remains visible, but uncovered
non-critical lines no longer produce a failed check like Comfy-Org#13750.

## verification

Comfy-Org#13775 (comment)

## Review Focus

Critical coverage is still enforced by the required `CI: Tests Unit`
job. This only changes the external Codecov status from blocking-style
failure to informational reporting.

Validated with Codecov's YAML validator, `pnpm exec oxfmt --check
codecov.yml`, and the pre-push `knip` hook.

Created by Codex

Co-authored-by: huang47 <157390+huang47@users.noreply.github.com>

Author: huang47

codecov.yml

@@ -1,3 +1,9 @@
+coverage:
+  status:
+    patch:
+      default:
+        informational: true
+
 comment:
   layout: 'header, diff, flags, files'
   behavior: default