fix(mcp): remove incorrect absolute path validation for Claude Desktop

Claude Desktop accepts both absolute and relative paths for commands,
resolving them at runtime using the system PATH. The validation logic
incorrectly enforced absolute path requirements that Claude Desktop
itself does not have.

Changes:
- Remove Path.is_absolute() check from ClaudeHostStrategy.validate_server_config()
- Accept any command (relative or absolute) or URL
- Update test mock to match fixed behavior
- Add documentation explaining Claude Desktop's actual behavior

Evidence: User's working configuration contains relative path 'mamba'
that was successfully synced and functions correctly in Claude Desktop.

Impact:
- Fixes: hatch mcp configure fails for claude-desktop with relative paths
- Backward compatible: absolute paths still work
- Test results: 284/286 MCP tests passing (2 unrelated failures)

Root cause: Misinterpretation of Claude Desktop requirements led to
overly restrictive validation that didn't match actual behavior.

Author: LittleCoinCoin

hatch/mcp_host_config/strategies.py

@@ -30,12 +30,21 @@ def get_config_key(self) -> str:
         return "mcpServers"
 
     def validate_server_config(self, server_config: MCPServerConfig) -> bool:
-        """Claude family validation - requires absolute paths for local servers."""
+        """Claude family validation - accepts any valid command or URL.
+        
+        Claude Desktop accepts both absolute and relative paths for commands.
+        Commands are resolved at runtime using the system PATH, similar to
+        how shell commands work. This validation only checks that either a
+        command or URL is provided, not the path format.
+        """
+        # Accept local servers (command-based)
         if server_config.command:
-            # Claude Desktop requires absolute paths
-            if not Path(server_config.command).is_absolute():
-                return False
-        return True
+            return True
+        # Accept remote servers (URL-based)
+        if server_config.url:
+            return True
+        # Reject if neither command nor URL is provided
+        return False
 
     def _preserve_claude_settings(self, existing_config: Dict, new_servers: Dict) -> Dict:
         """Preserve Claude-specific settings when updating configuration."""

tests/test_mcp_host_registry_decorator.py

@@ -301,10 +301,10 @@ def __init__(self):
                 self.config_format = "claude_format"
 
             def validate_server_config(self, server_config):
-                # Claude family requires absolute paths
-                if server_config.command:
-                    return Path(server_config.command).is_absolute()
-                return True
+                # Claude family accepts any valid command or URL
+                if server_config.command or server_config.url:
+                    return True
+                return False
 
         @register_host_strategy(MCPHostType.CLAUDE_DESKTOP)
         class TestClaudeDesktop(TestClaudeBase):