[BUG] Local-scoped MCP servers not persisted to project settings.local.json file

According to the https://docs.anthropic.com/en/docs/claude-code/mcp, MCP servers should be stored in local project settings by
default when using claude mcp add. However, local-scoped MCP servers are not being written to the expected
.claude/settings.local.json file.

Steps to reproduce:

1. Navigate to a project directory with a .claude/settings.local.json file
2. Run claude mcp add --scope local test-server echo "test"
3. Verify the server was added with claude mcp list
4. Check .claude/settings.local.json for the MCP server configuration

Expected behavior:
The MCP server configuration should appear in .claude/settings.local.json as documented.

Actual behavior:

• The server is successfully added and appears in claude mcp list
• The server is functional (can be used)
• However, no MCP configuration is written to .claude/settings.local.json
• No new files are created in the .claude/ directory

Environment:

• OS: macOS (Darwin 24.5.0)
• Claude Code version: [latest]

Additional context:
The claude mcp add command reports "Added stdio MCP server test-server with command: echo test to local config" but the
configuration doesn't persist to the documented location. This makes it unclear where local-scoped MCP servers are actually
stored and may cause confusion about project-specific MCP configuration.