Remove Shortcut references from UI to make AutoPR tool-agnostic

[Neokil]

Problem

The web UI contains hardcoded references to Shortcut — in button labels, copy, and component logic. This makes AutoPR appear to be a Shortcut-only tool, even though the backend is designed to be integration-agnostic. Users running AutoPR with a different ticketing system (or no ticketing system at all) see confusing or irrelevant UI text.

Solution

1. Audit the frontend for all Shortcut-specific strings and references (component text, tooltips, placeholder copy).
2. Replace them with generic equivalents (e.g. "ticket" instead of "Shortcut story", "discover" instead of "find in Shortcut").
3. Move any remaining Shortcut-specific logic into prompt templates, which are the intended place for integration knowledge.
4. Verify no Shortcut branding remains visible in the UI when running without Shortcut configured.