Code completion plugin for reovim

This plugin provides auto-completion functionality:

• Trigger completion popup
• Navigate suggestions with next/prev
• Confirm selection or dismiss

Architecture

This plugin follows the treesitter decoupling pattern:

• Defines SourceSupport trait for external sources to implement
• Uses background saturator for non-blocking completion
• Uses ArcSwap cache for lock-free render access
• Communicates via EventBus events