Wiki: "LSP: Getting started" should cover code actions, and `cue lsp` should no longer be hidden

[myitcv]

The wiki at https://github.com/cue-lang/cue/wiki/LSP:-Getting-started is a good on-ramp, but there are two concrete gaps worth addressing:

1. cue lsp should no longer be hidden

cmd/cue/cmd/lsp.go:29 still marks the subcommand as Hidden: true. Given the feature set below is real and user-facing, it's probably time to unhide it (and flesh out the TODO(myitcv) items in that file around flag processing and cue help lsp).

2. Code actions (refactors) exposed by the server

internal/lsp/server/codeaction.go ships three concrete refactors that users get via textDocument/codeAction. None are mentioned on the wiki:

• Add surrounding struct braces (refactor.rewrite.convertToStruct) — wraps the selection in { ... }.
• Remove surrounding struct braces (refactor.rewrite.convertFromStruct) — the inverse; marked IsPreferred so editors prioritise it when both apply.
• Organize Imports (source.organizeImports).

A short subsection with a screenshot or gif and editor-specific keybinding hints (e.g. Ctrl+. in VSCode, <leader>ca in common Neovim setups) would go a long way.

[mvdan]

I agree on both accounts. The LSP is pretty much stable and documented at this point. And indeed a new LSP user may not be aware of what code actions we support at all, as discovering them can be tricky - you need to know when they trigger to see them.