Switch to latest proof with fail-level warn

The latest channel is now live at downloads.reqproof.com/releases/latest/.
No version pin needed — proof-action@v1 defaults to latest.
Switch fail-level to warn for strict enforcement.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: buger

.github/workflows/reqproof.yml

@@ -23,10 +23,8 @@ jobs:
           path: ~/.proof/solvers
           key: proof-solvers-${{ runner.os }}
 
-      # Pin to current release until latest channel is populated
       - uses: probelabs/proof-action@v1
         with:
-          version: '0.1.0-main.20260404054230'
-          fail-level: error
+          fail-level: warn
           scope: full
           format: markdown