add .gitignore and CI workflow for markdown linting

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: kevinten10

.github/workflows/ci.yml

@@ -0,0 +1,69 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+
+jobs:
+  markdown-lint:
+    name: Markdown Lint
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Lint Markdown files
+        run: npx markdownlint-cli2 "**/*.md" "#node_modules"
+
+  check-links:
+    name: Check Internal Links
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Check for broken internal links
+        shell: bash
+        run: |
+          rm -f /tmp/broken_links_found
+
+          while IFS= read -r file; do
+            dir="$(dirname "$file")"
+
+            # Extract link targets from markdown [text](target) syntax
+            grep -oE '\]\([^)]+\)' "$file" \
+              | sed 's/^\](//;s/)$//' \
+              | while IFS= read -r link; do
+
+              # Skip external URLs, pure anchors, and absolute paths
+              case "$link" in
+                http://*|https://*|mailto:*|ftp://*) continue ;;
+                \#*) continue ;;
+                /*) continue ;;
+              esac
+
+              # Strip anchor fragment for file existence check
+              target="${link%%#*}"
+              [ -z "$target" ] && continue
+
+              # Resolve relative to the file's directory
+              resolved="$dir/$target"
+
+              if [ ! -e "$resolved" ]; then
+                echo "::error file=${file}::Broken link: ${link} (resolved to ${resolved})"
+                # Write to a temp file to propagate failure out of the pipe subshell
+                echo "1" > /tmp/broken_links_found
+              fi
+            done
+          done < <(find . -name '*.md' -not -path './node_modules/*')
+
+          if [ -f /tmp/broken_links_found ]; then
+            echo ""
+            echo "Found broken internal links. See errors above."
+            exit 1
+          fi
+
+          echo "All internal links are valid."

.gitignore

@@ -0,0 +1,11 @@
+# OS files
+.DS_Store
+Thumbs.db
+
+# Editor swap files
+*.swp
+*.swo
+
+# IDE directories
+.vscode/
+.idea/