Add JSON-RPC notification detection and response suppression per MCP spec. Notifications (requests without "id" field) must never receive responses, even if the upstream server returns an error. Prevents handshake failures when Claude Code sends notifications/initialized and receives unexpected error responses.
Changes:
- Add isJsonRpcNotification() to detect requests without "id" field
- Skip error responses for notifications
- Suppress upstream responses to notifications
- Add detailed comments explaining JSON-RPC 2.0 notification semantics
Replace Content-Length framing with newline-delimited JSON (NDJSON) for MCP stdio transport. MCP clients like Claude Code expect one JSON object per line, not LSP-style Content-Length headers. The previous framing caused clients to reject responses.
Adds writeFramed helper to send responses with HTTP-style Content-Length headers instead of raw JSON lines. Ensures compatibility with Claude Code which expects framed messages. Updates both main loop and writeResponse to use consistent framing.
Implements readMessage function to handle both raw JSON lines and Content-Length framed messages. Claude Code uses HTTP-style framing (Content-Length: N\r\n\r\n{json}) while other clients may send raw JSON. Auto-detects format by peeking at first bytes. Adds .gitignore for compiled binaries.
