feat: implement git repository management

- Add backend API for git repository CRUD (create, list, delete)
- Support bare repository initialization and mirror cloning
- Add cascade delete for repositories when project is deleted
- Add frontend page for repository management per project
- Update project page with link to repositories
- Add repo_base_path to config
- Quality gates: ruff, mypy, typecheck, lint, build all pass

apps/web/src/pages/projects.tsx

@@ -1,5 +1,7 @@
 import { useCallback, useEffect, useState } from "react";
 
+import { Link } from "react-router-dom";
+
 import {
   createProject,
   deleteProject,
@@ -134,6 +136,9 @@ export const ProjectsPage = () => {
                 {project.description && <p className="muted">{project.description}</p>}
               </div>
               <div className="project-actions">
+                <Link className="ghost-button" to={`/projects/${project.id}/repositories`}>
+                  Repositories
+                </Link>
                 <button
                   className="ghost-button"
                   onClick={() => openEdit(project)}