feat: add markdown link validation to CI

.github/workflows/ci.yml

@@ -177,3 +177,21 @@ jobs:
 
           echo "$errors template validation failures"
           exit $errors
+
+  check-links:
+    name: Check Markdown Links
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Check markdown links
+        uses: lycheeverse/lychee-action@v2
+        with:
+          args: >-
+            --verbose
+            --no-progress
+            --config .lychee.toml
+            '*.md'
+            'docs/**/*.md'
+          fail: true

.lychee.toml

@@ -0,0 +1,40 @@
+# Lychee link checker configuration
+# https://lychee.cli.rs/usage/config/
+
+# Directories and files to exclude from checking
+exclude_path = [
+  "node_modules",
+  ".git",
+  "pnpm-lock.yaml",
+  ".claude"
+]
+
+# Max number of retries per request (handles transient failures)
+max_retries = 3
+
+# Timeout per request in seconds
+timeout = 30
+
+# Max concurrent requests (avoid rate limiting)
+max_concurrency = 5
+
+# Accept 200..=299 status codes
+accept = [200, 201, 202, 203, 204, 206, 429]
+
+# Exclude URLs that are known to block automated checks or are placeholders
+exclude = [
+  # Patreon blocks automated requests
+  "https://www.patreon.com/.*",
+  # Shield badge images (always valid if the URL format is correct)
+  "https://img.shields.io/.*",
+  # Contributor Covenant version-specific URLs may redirect
+  "https://www.contributor-covenant.org/version/.*",
+  # Example/placeholder URLs
+  "https://example.com.*"
+]
+
+# Don't fail on URLs behind authentication or known to be flaky
+exclude_all_private = true
+
+# Skip checking mail addresses
+include_mail = false