docs: behaviors.md missing icon API, tile zoom update, and other undocumented endpoints

[evan-zhang11]

Documentation Gaps (2026-05-21)

Undocumented Endpoints in routes.rs:

1. Icon API (completely undocumented) - GET/POST /api/icons, PATCH/DELETE /api/icons/{id}, GET /api/icons/{id}/file
2. Tile Zoom Update - PATCH /api/files/{id}/zoom (update minZoom/maxZoom for published dynamic data)
3. Font Delete - DELETE /api/fonts/{id} not in API-020
4. Archived Workspaces - GET /api/workspaces/archived undocumented
5. Leave Workspace - POST /api/workspaces/{id}/leave not in WS-007

Recommendation:

Add behavior entries for icon CRUD, tile zoom, update existing entries. P1.