ci: add relative link checker

Author: OgeonX-Ai

scripts/check_links.py

@@ -0,0 +1,32 @@
+from pathlib import Path
+import re
+
+ROOT = Path(__file__).resolve().parents[1]
+LINK_RE = re.compile(r'\[[^\]]+\]\(([^)]+)\)')
+SKIP_PREFIXES = ('http://', 'https://', 'mailto:', '#')
+
+errors = []
+for md in ROOT.rglob('*.md'):
+    text = md.read_text(encoding='utf-8')
+    for match in LINK_RE.finditer(text):
+        target = match.group(1).split('#', 1)[0].strip()
+        if not target or target.startswith(SKIP_PREFIXES):
+            continue
+        if target.startswith('../') or target.startswith('./'):
+            resolved = (md.parent / target).resolve()
+        else:
+            resolved = (md.parent / target).resolve()
+        try:
+            resolved.relative_to(ROOT.resolve())
+        except ValueError:
+            continue
+        if not resolved.exists():
+            errors.append(f'{md.relative_to(ROOT)} -> {target}')
+
+if errors:
+    print('Broken relative links:')
+    for error in errors:
+        print('-', error)
+    raise SystemExit(1)
+
+print('Relative links OK')