Add preview-first Gmail contact discovery sweep for RUDI CRM

[rudijetson]

Problem

RUDI CRM has discovery contracts and Google Workspace can return header-only Gmail pages, but operators lack one bounded CLI workflow that joins them safely. Manual sweeps are difficult to reproduce and make preview-versus-write behavior ambiguous.

Scope

• add rudi crm sweep-gmail with explicit account and date bounds
• read only From, To, Cc, and Bcc metadata and exclude spam/trash
• default to a private preview artifact with no CRM writes
• gate idempotent discovery recording behind --record
• never create, merge, attach, or promote CRM people
• paginate defensively, validate provider responses, and bound batch sizes
• add a small MCP stdio client for canonical RUDI router tool calls

Acceptance

• explicit account and valid date window are required
• default artifact is owner-only and preview mode performs no CRM writes
• record mode uses only discovery/heuristic/log/validator contracts
• repeated pagination tokens and malformed provider data fail closed
• MCP startup/shutdown failures settle without hanging
• focused/full tests, build, debt scan, package dry run, and diff checks pass