fix(wiki): exclude URL-shaped bibkeys from claim parsing

_parse_claims now skips matches where bibkey contains spaces or starts
with "http", preventing Markdown hyperlinks like [text](https://...) from
being misidentified as citations. Add two tests.

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

codex/wiki.py

@@ -228,6 +228,10 @@ def _parse_claims(markdown: str) -> list[Claim]:
         text = match.group("text").strip()
         bibkey = match.group("bibkey").strip()
         locator = (match.group("locator") or "").strip()
+        # Skip URL-shaped bibkeys ([text](https://...)) and multi-word bibkeys
+        # (real BibKeys never contain spaces or start with "http")
+        if " " in bibkey or bibkey.startswith("http"):
+            continue
         if text and bibkey:
             claims.append(Claim(text=text, bibkey=bibkey, locator=locator))
     return claims