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/router.tsx

@@ -7,6 +7,7 @@ import { LoginRedirectPage, NotFoundPage } from "./pages/placeholder";
 import { ProfilePage } from "./pages/profile";
 import { ProjectsPage } from "./pages/projects";
 import { GitRepositoriesPage } from "./pages/git-repositories";
+import { GitHistoryPage } from "./pages/git-history";
 import { SSHKeysPage } from "./pages/ssh-keys";
 import { SettingsPage } from "./pages/settings";
 import { ToolTypesPage } from "./pages/tool-types";
@@ -26,6 +27,7 @@ export const AppRouter = () => {
         <Route index element={<DashboardPage />} />
         <Route path="projects" element={<ProjectsPage />} />
         <Route path="projects/:projectId/repositories" element={<GitRepositoriesPage />} />
+        <Route path="projects/:projectId/repositories/:repoId/history" element={<GitHistoryPage />} />
         <Route path="ssh-keys" element={<SSHKeysPage />} />
         <Route path="profile" element={<ProfilePage />} />
         <Route path="settings" element={<SettingsPage />} />