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>

tests/test_registry.py

@@ -128,6 +128,7 @@ description: Base agent with no dependencies
     dependent_agent = """---
 name: dependent-agent
 description: Agent that depends on base-agent
+dependencies: ["base-agent"]
 ---
 
 # Dependent Agent
@@ -138,6 +139,7 @@ This agent uses base-agent for functionality.
     complex_agent = """---
 name: complex-agent
 description: Agent with multiple dependencies
+dependencies: ["base-agent", "dependent-agent"]
 ---
 
 # Complex Agent
@@ -188,23 +190,26 @@ description: A valid agent
 # Valid Agent
 """
 
-    # Create invalid agent (missing required fields)
-    invalid_agent = """---
-description: Missing name field
+    # Create agent with missing dependency
+    missing_dep_agent = """---
+name: missing-dep-agent
+description: Agent with missing dependency
+dependencies: ["non-existent-agent"]
 ---
 
-# Invalid Agent
+# Missing Dependency Agent
 """
 
     (tmp_path / "agent-valid-agent.md").write_text(valid_agent)
-    (tmp_path / "agent-invalid-agent.md").write_text(invalid_agent)
+    (tmp_path / "agent-missing-dep-agent.md").write_text(missing_dep_agent)
 
     registry = AgentRegistry(tmp_path)
 
     errors = registry.validate_agents()
-    # The invalid agent should not be loaded, so no validation errors
-    # (it fails during loading)
-    assert len(errors) == 0  # Because invalid agents aren't loaded
+    # Should have one error for missing dependency
+    assert len(errors) == 1
+    assert "missing-dep-agent" in errors
+    assert "Missing dependency: non-existent-agent" in errors["missing-dep-agent"]
 
 
 def test_agent_category_determination():