fix: invert *_ready getters to fix server status indicator

[Brendonovich]

Summary

The server status indicator dot in the top bar was always grey instead of green because the *_ready getters (mcp_ready, provider_ready, lsp_ready) in child-store.ts were returning query.isLoading instead of !query.isLoading.

Since TanStack Query's isLoading is true during fetching and false once data is available, these getters were semantically inverted — "ready" was true only while loading and false after data arrived.

Changes

• Invert provider_ready, mcp_ready, and lsp_ready getters to return !query.isLoading

[Eric-Guo]

This PR break model selecting box