Prefer client pull diagnostics over server push

[KevinEady]

Fixes: #93

References:

• https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_diagnostic
• https://github.com/microsoft/vscode/issues/205790#issuecomment-1962943279

[KevinEady]

Old behavior:

https://github.com/user-attachments/assets/f63c4d99-4200-4b16-aebb-f231152eebe9

---

New behavior:

https://github.com/user-attachments/assets/7c3d4129-a01b-4996-8845-fe3cf7a2d5db

[KevinEady]

Any thoughts on this merge request...? I can rebase the branch if so.