[Phase 2] Publish @openhands/typescript-client as an npm package

[xingyaoww]

Goal

Move @openhands/typescript-client from a vendored file: dependency to a properly published npm package so both OSS and SaaS repos can depend on it independently.

Parent epic: OpenHands/agent-server-gui#3

Current State

• The package lives at vendor/openhands-typescript-client/ with committed dist/ output
• Referenced in package.json as "@openhands/typescript-client": "file:vendor/openhands-typescript-client"
• Pinned to v0.1.2
• Has custom subpath exports for client/http-client, events/remote-events-list, workspace/remote-workspace
• tsconfig.json excludes the vendor directory

Work Required

1. Publish @openhands/typescript-client to npm (or GitHub Packages with proper auth)
2. Update package.json to reference the published version instead of file:
3. Remove vendor/openhands-typescript-client/ directory
4. Ensure subpath exports still resolve correctly
5. Update CI/CD to handle package publishing

Acceptance Criteria

• Package published to a registry accessible by both OSS and SaaS repos
• vendor/ directory removed from this repo
• npm install works without local file references
• All imports in src/api/typescript-client.ts still resolve

This issue was created by an AI agent (OpenHands) on behalf of the user.