Add shared dashboard organization: folders + project/org “golden” stars

### Problem Statement

## Summary
Provide first-class ways to organize and curate dashboards at scale:
- Shared **folders** (org- and/or project-scoped)
- **Curated stars** (“golden dashboards”) visible to everyone per project/org

## Problem
- Starring is **per-user only**; doesn’t help teams discover what’s canonical.
- Dashboard list grows rapidly; sorting isn’t enough.
- Teams need a way to highlight vetted dashboards for a project so newcomers know what to trust.

### Solution Brainstorm

## Proposal
1. **Folders**
- Create/manage folders (org-level and project-level).
- Move dashboards into folders; support drag/drop and bulk move.
- Folder permissions inherit from project/org.
2. **Curated Stars (“Golden”)**
- Allow project/org maintainers to mark dashboards as **Golden**.
- Golden dashboards appear pinned at the top of the project’s Dashboard view for all users.

## Acceptance Criteria
- [ ] Users can create shared folders and move dashboards into them.
- [ ] Folder structure visible to all users with access to the project/org.
- [ ] Maintainers can mark/unmark a dashboard as **Golden** at project and/or org scope.
- [ ] Golden dashboards render in a dedicated, pinned section (“Recommended”/“Golden”) ahead of others.
- [ ] API support for creating folders, moving dashboards, and setting Golden status.
- [ ] Migration: existing dashboards remain accessible; no data loss.

## Impact
Reduces noise and improves discoverability/governance of “the right” dashboards as adoption grows.

### Product Area

Dashboards

No files, tests, or entry points are identified, so begin by locating the dashboard organization and API implementations in the repository. Done means shared folders, project/org Golden status, pinned rendering, API support, and migration without data loss all meet the listed acceptance criteria.

Written by the indexing model from the issue text.