Add --frozen flag to uv run commands in Claude config

When generating Claude Desktop configuration files, the uv run commands
now include the --frozen flag. This prevents uv from updating lock files
when Claude Desktop launches MCP servers.

Without this flag, running MCP servers could inadvertently update uv.lock,
potentially causing issues in development environments and CI pipelines.
The --frozen flag ensures dependency resolution uses the existing lock
file without modifications.

This also fixes test_command_execution which was executing uv run without
--frozen, causing spurious lock file updates during test runs.

Author: maxisbey

src/mcp/cli/claude.py

@@ -99,7 +99,7 @@ def update_claude_config(
                 env_vars = existing_env
 
         # Build uv run command
-        args = ["run"]
+        args = ["run", "--frozen"]
 
         # Collect all packages in a set to deduplicate
         packages = {MCP_PACKAGE}