Document daily workstation operations

[priithunt]

What changed

• document the single daily operator interface for status, sync, maintenance, reports, and application review
• explain the M3-only weekly read-only maintenance overview
• describe keep, review, and migration-blocked application decisions
• keep strict release, lifecycle, backup, mail, and service operations outside the daily interface

Why

P2 makes routine two-Mac operations easier to discover while preserving the boundary between everyday configuration and exceptional lifecycle or service work.

Validation

• private curated source exact check: 45 files passed
• private-to-public path and content comparison: passed
• public scripts/verify-showcase.sh: passed