Tasks

1. Implementation

• 1.1 Extract getAvailableChanges in shared.ts and use it in statusCommand to check for changes before calling validateChangeExists
• 1.2 In text mode: print No active changes. Create one with: openspec new change <name> and return (exit 0)
• 1.3 In JSON mode: output {"changes":[],"message":"No active changes."} and return (exit 0)

2. Tests

• 2.1 Add test: openspec status with no changes exits gracefully with friendly message (text mode)
• 2.2 Add test: openspec status --json with no changes returns valid JSON with empty changes array
• 2.3 Verify existing behavior: openspec status without --change when changes exist still throws missing option error
• 2.4 Verify cross-platform: tests use path.join() for any path assertions

3. Release

• 3.1 Add changeset describing the fix