RFC 0010: Epic / Tracking issue for backup profiles

[rmanibus]

Context

Track completion and rollout for RFC 0010 (Backup Profiles).

RFC: rfcs/0010-backup-profiles.md

Goal

Provide YAML-driven backup profiles with reusable store/auth references while preserving existing flag-based workflows.

Scope

• Profile config model and persistence (profiles.yaml).
• CLI commands for profile, auth, and store management.
• Backup execution via -profile, -all-profiles, and -auth-ref.
• Docs and completion updates.

Linked PR

• feat: backup profiles (RFC 0010) #86

[rmanibus]

Implementation PR: #86

[rmanibus]

Related groundwork PR: #80