feat: add git history visualization frontend

- Add API client functions for commit history and detail endpoints
- Create GitHistoryPage with commit list, graph visualization, and detail panel
- Add branch selector for viewing different branches
- Integrate history view into repository list with History button
- Add comprehensive CSS styles for history page layout

Quality gates: typecheck ✓, lint ✓, build ✓

apps/web/src/pages/git-repositories.tsx

@@ -1,5 +1,5 @@
 import { useCallback, useEffect, useRef, useState } from "react";
-import { useParams } from "react-router-dom";
+import { useNavigate, useParams } from "react-router-dom";
 
 import {
   createRepository,
@@ -16,6 +16,7 @@ type UrlValidationStatus = "idle" | "validating" | "valid" | "needs-parsing" | "
 
 export const GitRepositoriesPage = () => {
   const { projectId } = useParams<{ projectId: string }>();
+  const navigate = useNavigate();
   const [status, setStatus] = useState<RepoStatus>("loading");
   const [repositories, setRepositories] = useState<GitRepository[]>([]);
   const [showCreate, setShowCreate] = useState(false);
@@ -188,6 +189,13 @@ export const GitRepositoriesPage = () => {
                 <p className="muted">{repo.path}</p>
               </div>
               <div className="repository-actions">
+                <button
+                  className="secondary-button small"
+                  onClick={() => navigate(`/projects/${projectId}/repositories/${repo.id}/history`)}
+                  type="button"
+                >
+                  History
+                </button>
                 {deleteConfirmId === repo.id ? (
                   <div className="delete-confirm">
                     <span>Are you sure?</span>