[P3] Audit trail / activity feed

[hazeliscoding]

Problem

No record of who changed shared status, who removed a member, or what happened in a watch space over time. Important for trust.

Requirements

• Activity log table recording key events per watch space
• Events: anime added/removed, status changed, member joined/left, rating submitted
• GET /watchspaces/{id}/activity endpoint (paginated)
• Frontend: activity feed section on the dashboard or a dedicated tab

Acceptance Criteria

• Key actions in a watch space are recorded with actor, timestamp, and description
• Activity feed is visible to all watch space members
• Feed is paginated and loads efficiently

References

• Roadmap §7 — Observability & Operations