Add branch protection support to prevent deletion of protected branches

[Copilot]

Overview

This PR adds support for GitHub's branch protection feature in the CodeSandbox dashboard. Protected branches can no longer be removed from CodeSandbox, preventing accidental deletion of important branches.

Problem

Previously, the dashboard only prevented deletion of the default branch. However, GitHub allows repository administrators to protect additional branches (e.g., main, develop, release/*) using branch protection rules. The CodeSandbox UI was not respecting these protection settings, allowing users to potentially remove protected branches.

Solution

The fix adds support for the protected field from GitHub's API:

1. GraphQL Queries - Updated branch fragments to fetch the protected status from the backend
2. Type Definitions - Added the protected field to TypeScript types for type safety
3. UI Logic - Modified the branch menu to check both default branch status and protection status before allowing removal

Before

const canRemoveBranch = name !== defaultBranch;

After

const canRemoveBranch = name !== defaultBranch && !branch.protected;

Changes

• packages/app/src/app/overmind/effects/gql/dashboard/fragments.ts - Added protected field to branchFragment and branchWithPRFragment
• packages/app/src/app/graphql/types.ts - Added protected: boolean to BranchFragment and BranchWithPrFragment types
• packages/app/src/app/pages/Dashboard/Components/Selection/ContextMenus/BranchMenu.tsx - Updated logic to respect branch protection

Impact

• The "Remove branch from CodeSandbox" option will now be hidden for any branch that is either the default branch OR protected by GitHub
• Prevents accidental deletion of important protected branches
• Maintains backward compatibility with existing functionality
• No breaking changes - branches without protection continue to work as before

Testing

The changes are minimal and surgical, affecting only the branch removal logic. The implementation:

• ✅ Maintains type safety with proper TypeScript definitions
• ✅ Follows existing patterns for branch removal restrictions
• ✅ Is backward compatible with unprotected branches

Original prompt

branch protection

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[snyk-io]

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