Fix Spinner Updates During Compaction

Resolves: #769

Screencast from 2025-05-06 15-39-23.webm

Solution

Implemented concurrent spinner updates using tokio::join! to properly show progress during compaction:

• Created an async block for spinner updates that runs alongside compaction
• Eliminated need for SpinnerManager cloning
• Ensured proper cleanup after compaction completes

Changes

• Modified the compact command handler in crates/forge_main/src/ui.rs
• Replaced task spawning with concurrent execution using tokio::join!
• Added proper spinner cleanup after operation completes

Testing

The changes have been tested by:

1. Running the /compact command
2. Verifying spinner updates every 500ms with elapsed time
3. Confirming spinner stops properly after compaction completes

/claim #769