fix(extensions): support non-GitHub git URLs for extension installation

[d191]

TLDR

Fixes extension installation from local domain git servers (GitLab, Bitbucket, etc.) by catching errors from parseGitHubRepoForReleases and falling back to use the source URL directly.

Dive Deeper

When installing an extension from a self-hosted git server (e.g., https://gitlab.company.com/team/my-extension), the installation failed after user confirmation with:

 Invalid GitHub repository source: https://gitlab.company.com/team/my-extension. Expected "owner/repo" or a github repo uri.

The root cause was in packages/core/src/extension/extensionManager.ts - the getExtensionId function unconditionally called parseGitHubRepoForReleases() which only supports GitHub URLs.

Solution: Wrapped the call in try-catch. If parsing fails (non-GitHub URL), use the source URL as-is for generating the extension ID - same behavior as local type installations.

Reviewer Test Plan

1. Run npm install and npm run build
2. Try installing an extension from a non-GitHub git URL:
   qwen extensions install https://gitlab.company.com/team/test-extension
3. Verify the extension installs successfully
4. Run qwen extensions list to confirm the extension appears

Testing Matrix

	🍏	🪟	🐧
npm run	❓	❓	✅
npx	❓	❓	✅
Docker	❓	❓	❓
Podman	❓	-	-
Seatbelt	❓	-	-

Linked issues / bugs

Fixes #2538