feat: simplify git mounts to use direct URLs instead of repo references

- Change git mount schema from repo_id to remote_url
- Remove database lookups for git mount resolution
- Clone directly from URL at instance startup
- Simplify frontend UI to text input for Git URL
- Fix route ordering in git_repositories.py to prevent 422 errors
- Update all tests to use remote_url field

Breaking change: Git mounts now use remote_url instead of repo_id

apps/web/src/api/config_profiles.ts

@@ -25,7 +25,7 @@ export interface ConfigProfileMount {
 }
 
 export interface GitMount {
-  repo_id: string;
+  remote_url: string;
   source_path: string;
   target_path: string;
   branch?: string;