feat: implement single instance

[0xbrayo]

Important

Implement single-instance feature using tauri-plugin-single-instance to ensure only one app instance runs.

• Behavior:
  • Implement single-instance feature using tauri-plugin-single-instance in src-tauri/src/lib.rs.
  • Logs a message and quits if another instance is detected.
• Dependencies:
  • Add tauri-plugin-single-instance to Cargo.toml and Cargo.lock.
• Documentation:
  • Update README.md to mark single-instance feature as complete.

^{This description was created by for b42b85c. It will automatically update as commits are pushed.}

[ellipsis-dev]

👍 Looks good to me! Reviewed everything up to b42b85c in 25 seconds

More details

• Looked at 673 lines of code in 5 files
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• Skipped posting 1 drafted comments based on config settings.

1. src-tauri/src/lib.rs:46

• Draft comment:
  Using unwrap() can lead to panics if the value is not present. Consider handling the error gracefully or using expect() with a meaningful message.
• Reason this comment was not posted:
  Confidence changes required: 50%
  The use of unwrap() can lead to panics if the value is not present. It's better to handle the error gracefully.

Workflow ID: wflow_UFr0rcsSc0NwRV57

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[0xbrayo]

closes #15