Prepare extension for vscode-languageclient ^10 compatibility

[Copilot]

This updates the extension baseline to support vscode-languageclient ^10, which requires newer VS Code API/runtime expectations and package export-compatible TypeScript resolution. The change aligns dependency, engine, and compiler settings so the existing client integration remains compatible.

• Dependency and engine alignment

  • Upgraded vscode-languageclient from ^9.0 to ^10.0.0.
  • Raised engines.vscode to ^1.91.0 to match language client v10 requirements.
  • Updated @types/vscode to ^1.91.0 for type compatibility.

• TypeScript module resolution update

  • Switched tsconfig to Node16 module semantics:
    • module: "Node16"
    • moduleResolution: "node16"
  • This ensures TS resolves modern exports fields used by vscode-languageclient/LSP packages.

• Protocol import hardening

  • Replaced deep internal import with package public API export in src/protocol.ts to avoid brittle path coupling across major versions.

- import { ProtocolRequestType } from 'vscode-languageserver-protocol/lib/common/messages'
+ import { ProtocolRequestType } from 'vscode-languageserver-protocol'