Release v0.0.15

What's Changed

• Merge pull request #87 from indrazm/broadcast
• chore: bump version to 0.0.15 and update release workflow
• refactor(broadcast): update button style and improve type safety
• feat(broadcast): add broadcast email functionality
• Merge pull request #86 from indrazm/improve-admin-ux
• feat(ui): improve dashboard and sidebar styling and organization
• Merge pull request #85 from indrazm/delete-post-admin
• feat(posts): allow admin to access post dropdown menu