feat(code): cartes liées au code — branches, PRs, commits (issue #1)

app/code_links.py: appariement pur (#n dans titres/corps/messages,
numéro en jeton de branche). Client: list_branches/list_pulls/
list_commits. Badge sur les cartes (board + fragments live),
section Code lié du panneau détail, /api/issues/{o}/{r}/{n}/code.

app/gitea_client.py

@@ -341,6 +341,25 @@ class GiteaClient:
         self._cache_clear()
         return r.json()
 
+    async def list_branches(self, owner: str, repo: str) -> list[dict]:
+        """All branches of a repo (code links, issue #1)."""
+        return await self._get_all_pages(f"/repos/{owner}/{repo}/branches")
+
+    async def list_pulls(
+        self, owner: str, repo: str, state: str = "all"
+    ) -> list[dict]:
+        """All pull requests of a repo (code links, issue #1)."""
+        return await self._get_all_pages(
+            f"/repos/{owner}/{repo}/pulls", state=state
+        )
+
+    async def list_commits(
+        self, owner: str, repo: str, limit: int = 75
+    ) -> list[dict]:
+        """Most recent commits of a repo (code links, issue #1)."""
+        data = await self._get(f"/repos/{owner}/{repo}/commits", limit=limit)
+        return data if isinstance(data, list) else []
+
     async def set_issue_assignees(
         self, owner: str, repo: str, issue_number: int, logins: list[str]
     ) -> dict: