fix(nes): only request if attached and notify on display

[tris203]

Ensure NES requests are only sent if the client is attached to the current buffer. Notify the LSP client with "textDocument/didShowInlineEdit" only when a suggestion is actually displayed.

[Copilot]

Pull request overview

This PR enhances the Next Edit Suggestion (NES) feature by adding two safety checks: ensuring LSP requests are only sent when the client is attached to the buffer, and only notifying the LSP client when a suggestion is actually displayed to the user.

Key changes:

• Add buffer attachment check before sending NES requests
• Make _display_next_suggestion return a boolean indicating display success
• Send textDocument/didShowInlineEdit notification only when suggestion is displayed
• Enable error notifications for better debugging

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
lua/copilot-lsp/util.lua	Removed unnecessary diagnostic suppression comment for type checking
lua/copilot-lsp/nes/ui.lua	Modified _display_next_suggestion to return boolean indicating whether suggestion was displayed
lua/copilot-lsp/nes/init.lua	Added buffer attachment check, enabled error notifications, and made LSP notification conditional on successful display

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[AntoineGS]

Hey random note 🤣
They officially documented the feature now: https://github.com/github/copilot-language-server-release/#next-edit-suggestions
The only difference I can see is the telemetry feedback.