feat: support external repositories for git mounts

- Make project_id nullable in git_repositories table (migration)
- Allow external repos not tied to any project
- Update validation to allow user-owned external repos in git mounts
- Add /projects/repositories endpoint to list all user repos
- Update frontend to fetch all user repos for git mount selector
- TypeScript and build pass

apps/web/src/pages/config-profiles.tsx

@@ -19,7 +19,7 @@ import {
   type ResolvedProfile,
 } from "../api/config_profiles";
 import { listProjects } from "../api/projects";
-import { listRepositories, type GitRepository } from "../api/git_repositories";
+import { listAllUserRepositories, type GitRepository } from "../api/git_repositories";
 import type { Project } from "../types";
 import { listToolTypes, type ToolType } from "../api/tool_types";
 import { GitMountEditor } from "../components/git-mount-editor";
@@ -72,17 +72,13 @@ export const ConfigProfilesPage = () => {
       setProjects(projs || []);
       setToolTypes(types || []);
       
-      // Load repositories from all projects
-      const allRepos: GitRepository[] = [];
-      for (const project of projs || []) {
-        try {
-          const repos = await listRepositories(project.id);
-          allRepos.push(...repos);
-        } catch {
-          // Skip projects we can't access
-        }
+      // Load all user repositories (including external ones)
+      try {
+        const allRepos = await listAllUserRepositories();
+        setRepositories(allRepos);
+      } catch {
+        setRepositories([]);
       }
-      setRepositories(allRepos);
       
       setStatus("ready");
     } catch {