Frontend: Reviewer queue and submission detail workspace

[Cedarich]

Complexity: 200 points

Goal
Build a reviewer-facing workspace in the webapp for triaging project or grant submissions with clear review context and decision actions.

Acceptance Criteria

• Provides a list view for pending and in-review submissions.
• Submission detail view shows evidence status and decision history.
• Supports approve request-changes and reject actions once backend APIs are available.
• Handles empty loading and permission-denied states cleanly.