enhancement: phase 3 roadmap — add bulk admin workflows and smarter request creation

[electather]

Problem / motivation

A lot of real Seerr administration is collection-oriented rather than object-oriented.

Current workflows would benefit from:

• bulk operations for requests, watchlist, and blocklist management
• smarter request creation with duplicate detection and better defaults

Proposed solution

Add higher-level workflows that improve day-to-day admin and user actions.

Scope:

• bulk approve/decline/retry request flows
• bulk watchlist/blocklist cleanup operations where appropriate
• smarter request creation with duplicate detection and clearer preflight feedback
• improved selection of server/profile defaults where feasible

Alternatives considered

Continue exposing only single-item CRUD style actions. This keeps the API surface simpler but misses a lot of practical workflow value.

Additional context

This issue intentionally excludes TUI work.

Suggested checklist:

• Design bulk operation UX and safety model
• Add dry-run or confirmation support where needed
• Add duplicate detection before request creation
• Add tests for workflow behaviour