feat: comprehensive CLI testing and fetch functionality fixes

- Add comprehensive CLI command and subcommand tests (108 tests total)
  - 89 tests for all CLI commands, subcommands, parameters, and options
  - 19 tests for CLI option definitions and validation
  - Tests for main commands: version, doctor, upgrade/install, uninstall, launch
  - Tests for config commands: validate, list, set, unset, show
  - Tests for all subcommand groups: skill, agent, plugin, mcp, extensions, prompt

- Fix critical tuple unpacking bug in base.py fetch functionality
  - Fixed with git_repo.clone() as (temp_dir, actual_branch) instead of as temp_dir
  - Bug was introduced in last commit (4740d6e) during unified fetching framework

- Improve error handling in repository.py clone method
  - Better RuntimeError instead of re-raising CalledProcessError when all branches fail
  - Simplified cleanup logic to always call rmtree with ignore_errors

- Add regression tests to prevent future tuple unpacking issues
  - Test clone method returns correct tuple structure
  - Integration test for proper tuple unpacking in fetchers

- Fix test mocking issues in parallel fetching tests
  - Corrected as_completed mocking to handle dictionary iteration properly

- Verify all fetch commands work correctly
  - skill fetch: ✅ Found 1323 skills
  - agent fetch: ✅ Found 1355 agents
  - plugin marketplace add: ✅ Working with proper validation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: James Zhu

code_assistant_manager/fetching/base.py

@@ -133,7 +133,7 @@ def _fetch_from_single_repo(self, repo: RepoConfig) -> List[T]:
 
         try:
             # Clone/download repository
-            with git_repo.clone() as temp_dir:
+            with git_repo.clone() as (temp_dir, actual_branch):
                 # Determine scan directory
                 scan_dir = temp_dir
                 if repo.path:

code_assistant_manager/fetching/repository.py

@@ -64,7 +64,8 @@ def clone(self) -> Generator[Tuple[Path, str], None, None]:
                     break
                 except subprocess.CalledProcessError:
                     if branch == branches_to_try[-1]:
-                        raise
+                        # All branches failed, raise RuntimeError instead of CalledProcessError
+                        raise RuntimeError(f"Failed to clone repository from any branch")
                     logger.debug(f"Branch {branch} not found, trying next...")
 
             if not success:
@@ -74,5 +75,4 @@ def clone(self) -> Generator[Tuple[Path, str], None, None]:
 
         finally:
             # Cleanup
-            if temp_dir.exists():
-                shutil.rmtree(temp_dir, ignore_errors=True)
+            shutil.rmtree(temp_dir, ignore_errors=True)