Point lychee to config file explicitly

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: tobixen

.github/workflows/linkcheck.yml

@@ -12,6 +12,7 @@ jobs:
       with:
         fail: true
         args: >-
+          --config .lychee.toml
           --timeout 10
           --max-retries 2
           '**/*.md'