Remove paths filter to allow mandatory check

The paths filter prevented the workflow from running on non-proposal PRs.
When the check is configured as mandatory in branch protection, GitHub
blocks merges if the check hasn't run.

Removing the filter allows the check to run on all PRs and pass cleanly
when there are no proposal files, making it safe to require.

Addresses feedback from robobario in PR kroxylicious#104.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: k-wall

.github/workflows/proposal-numbering.yml

@@ -13,8 +13,6 @@ name: Check Proposal Numbering
 on:
   pull_request:
     types: [opened, synchronize, reopened]
-    paths:
-      - 'proposals/*.md'
 
 permissions:
   pull-requests: write