Add label completions

[gabritto]

No description provided.

[Copilot]

Pull Request Overview

Adds support for showing label completions after break/continue statements.

• Introduce an early branch in getCompletionsAtPosition to call new label-completion helpers
• Implement getLabelCompletionsAtPosition and getLabelStatementCompletions
• Update the AST alias list and add tests covering various label-completion scenarios

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
internal/ls/completions_test.go	New tests under TestCompletions for break/continue label suggestions
internal/ls/completions.go	Added logic to detect break/continue context and return label completions
internal/ast/ast.go	Extended Node aliases with BreakOrContinueStatement

Comments suppressed due to low confidence (1)

internal/ls/completions.go:4137

• [nitpick] the name uniques is ambiguous; consider renaming to seenLabels or uniqueLabels to clarify that it tracks which label names have already been added.

var uniques core.Set[string]