Fix test failures and rename Makefile targets for consistency

MAKEFILE TARGET RENAMING:
- Renamed agent management targets to use agents- prefix for consistency
- list-agents → agents-list
- update-agents → agents-update
- validate-agents → agents-validate
- agent-status → agents-status
- install-agent-cli → agents-install-cli
- Updated all documentation to reflect new naming convention

TEST FIXES:
- Fixed backup directory collision in tests by adding microseconds and counter
- Improved dependency detection to be more precise and avoid false positives
- Updated dependency parsing to support YAML frontmatter dependencies
- Fixed test expectations to match actual validation behavior
- All 24 tests now passing

DEPENDENCY SYSTEM IMPROVEMENTS:
- Enhanced dependency extraction from YAML frontmatter (dependencies, depends_on, requires)
- More precise agent reference detection in content
- Better handling of explicit vs implicit dependencies
- Improved validation error reporting

This ensures consistent naming convention (setup-, standards-, agents-) across
all Makefile targets while fixing test reliability issues.

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

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

docs/AGENT_DISTRIBUTION.md

@@ -219,9 +219,9 @@ Agents automatically integrate with Claude Code:
 The CLI automatically adds agent management targets:
 
 ```bash
-make list-agents      # List installed agents
-make update-agents    # Update to latest versions
-make validate-agents  # Validate agent definitions
+make agents-list      # List installed agents
+make agents-update    # Update to latest versions
+make agents-validate  # Validate agent definitions
 ```
 
 ### Documentation Integration