Build embeddable issue widget for external sites and docs #18

Problem

As a SaaS product, OpenGrove needs a way for users to embed issue status, progress bars, or feedback widgets into their own documentation, README files, or customer-facing status pages.

Use Cases

• Embed a 'Report a bug' widget on your docs site that creates an OpenGrove issue
• Show project progress (e.g., 12/20 issues done) in a README badge
• Status page widget showing open incidents

Acceptance Criteria

• Public API endpoint for issue/project status (read-only, no auth needed for public projects)
• Embeddable script tag that renders a mini widget
• Badge URL for README markdown (like shields.io)
• Respects org privacy settings - only public projects are exposed
• Enterprise feature: custom branding on widgets