fix: erros and improved code quality.

[geekyharsh05]

Changes

• Refactor: Extract duplicated Solana RPC endpoint to a constant for better maintainability
• Fix: Add proper error handling for tokens with undefined decimals to prevent runtime errors
• Update: Replace manual error toast construction with showFailureToast from @raycast/utils
• Update: Improve extension description to clearly explain functionality
• Fix: Replace reserved keyboard shortcut (cmd+w) with opt+w to avoid conflicts with Raycast system shortcuts
• Icon: Added new icon for the extension.

[geekyharsh05]

@devsargam