chore: drop /mcp/ws-port endpoint, simplify WS port discovery
WebSocket port is always HTTP port + 1, no need for endpoint.
- Remove /mcp/ws-port from README, tests, vite proxy
- Simplify mcpServiceFactory to sync (no fetch needed)
- Add PR.md with updated description
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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
