mcp: --mcp / configure mcp --location no longer clobbers other MCP servers

[sunishsheth2009]

Summary

Reported bug: "When I use the CLI parameter for a custom mcp it clears all my existing mcp configurations and I have to rerun configure again to get the built-in ones."

ucode configure --mcp system.ai.slack (and ucode configure mcp --location <schema> / --services) removed every other registered MCP server — external connections, Genie spaces, apps, Vector Search / UC functions, and mcp-services in other schemas — leaving only the just-configured location's services. The user then had to re-run configure mcp to restore the rest.

Cause

_resolve_location_mcp_servers returned only the services discovered at the target location (plus skills). apply_mcp_server_changes then removes any original server not present in that working set — so everything outside the location was deleted.

Fix

Scope the replacement to mcp-services in the target location. The resolver now carries through every original server that isn't a service in that location, matched by _is_mcp_service_in_location (which correctly rejects nested names like system.ai.sub.x and schema-prefix lookalikes like system.aiX.y). Behavior preserved:

• The location's own services are still strictly replaced — a stale in-location service that's no longer discovered is removed.
• Skills connections stay owned by configure skills (carried through untouched, as before).

How do you know it works?

• Verified via the real resolver: --mcp system.ai.github against a config holding a custom external (jira-mcp), a Genie space, and an other-schema service (main.tools.x) preserves all three and adds system-ai-github.
• Tests (tests/test_mcp.py, 132 pass): rewrote the test that codified the old clobber (test_replaces_servers_outside_location → test_preserves_servers_outside_the_location), added test_replaces_stale_service_within_the_location, and added TestIsMcpServiceInLocation edge-case coverage (nested names, prefix lookalikes, non-service entries, missing URL).
• Full suite: 1801 passed; the only 2 failures are the pre-existing test_e2e_user_agent live-gateway network tests (fail identically on main). ruff + ty check src/ clean.

Independent of the mcp-SDK-compat PR (#338) — different code path.

This pull request and its description were written by Isaac.