fix(server): hide mutating stdio tools in read-only mode fixes #281

[ahfoysal]

Summary

• Ensured createSupabaseMcpServer filters tools before registration when --read-only is enabled.
• The stdio transport now omits tools with readOnlyHint: false in read-only mode, so tools/list no longer exposes mutating actions.
• Kept existing behavior intact for adaptive tools (e.g. execute_sql) that remain visible with adjusted annotations.

Verification

• CI=1 ./node_modules/.bin/vitest run --project integration test/stdio.integration.ts

Closes #281

[raulb]

Hey! Thank you for your contribution! I was actually reviewing #283, which seems to fix the same core issue as #281.

That other PR adds something I particularly like: the fact that write tools are still registered, and it returns a nicer error when in read mode, e.g., "Cannot apply migration in read-only mode." This PR seems to remove that altogether, which I think provides a less-than-ideal UX.

I appreciate your contribution, though, so please keep them coming!