feat(duo): add direct proxy setting for LSP traffic

Summary

Adds a VS Code setting that forwards direct Duo proxy mode to the GitLab language server.

Scope

• Adds gitlab.duo.proxy.directConnection to the GitLab Duo settings category.
• Scopes the setting to the current machine so workspace configuration and Settings Sync cannot change proxy routing.
• Reads the setting through the extension configuration service.
• Sends duo.proxy.mode as direct when enabled and inherit when disabled.
• Keeps VS Code HTTP proxy settings unchanged for other extension and editor traffic.

Contract References

• Requires @gitlab-org/gitlab-lsp 9.7.0, which contains gitlab-org/editor-extensions/gitlab-lsp!3462 (merged) and exposes duo.proxy.mode on ClientConfig.
• The default false value maps to inherit so current proxy behavior is preserved.
• The true value maps to direct for scoped GitLab and Duo traffic handled by the language server.

Change Details

• Added the machine-scoped boolean setting to package.json with Duo category ordering.
• Added extension configuration typing and parsing for duo.proxy.directConnection.
• Extended the language server configuration payload with duo.proxy.mode using the published ClientConfig contract.
• Updated the LSP dependency and lockfile to 9.7.0.
• Added tests for config parsing, sync payload mapping, setting scope, and package setting order.

Validation Evidence

• Clean npm ci dependency installation.
• Prettier check on touched files and the lockfile.
• ESLint on touched TypeScript files.
• Focused Jest suites: 3 passed, 53 tests passed.
• TypeScript compilation with no emitted output.
• Full Jest suite: 290 passed, 2,482 tests passed.
• Production VSIX packaging.

Risks and Follow-ups

• The direct mode is opt-in and preserves inherited proxy behavior by default.
• Custom proxy URL mode is intentionally not included.
• JetBrains and docs are handled in separate MRs.

Issue Reference

Relates to gitlab-org/editor-extensions/gitlab-lsp#2490 (closed)