notebooklm-upstream-auth-format-two-files

The upstream notebooklm-mcp-cli uses two auth files: profiles/default/cookies.json (30 cookies in AuthTokens format) and profiles/default/metadata.json, controlled via NOTEBOOKLM_MCP_CLI_PATH env var pointing to the config dir. The old notebooklm-py format used a single storage_state.json. CSRF token and session ID are auto-extracted by upstream on first API call — only cookies are needed for initial migration.