Language server capabilities

InterlisLanguageServer#initialize wires up the capabilities exposed to clients. The resulting payload looks like:

{
  "capabilities": {
    "positionEncoding": "utf-16",
    "textDocumentSync": {
      "openClose": true,
      "change": 2,
      "save": {
        "includeText": false
      }
    },
    "completionProvider": {
      "triggerCharacters": [".", ":"],
      "resolveProvider": false
    },
    "documentFormattingProvider": true,
    "documentOnTypeFormattingProvider": {
      "firstTriggerCharacter": "="
    },
    "definitionProvider": true,
    "renameProvider": true,
    "documentSymbolProvider": true,
    "executeCommandProvider": {
      "commands": [
        "interlis.compile",
        "interlis.uml",
        "interlis.uml.plant"
      ]
    }
  }
}

Key listeners and providers derived from these capabilities:

Event / Provider	Implementation	Notes
`textDocument/didOpen`	`InterlisTextDocumentService#didOpen`	Compiles freshly opened files and streams diagnostics.
`textDocument/didChange`	`InterlisTextDocumentService#didChange`	Updates the in-memory document tracker & invalidates caches.
`textDocument/didSave`	`InterlisTextDocumentService#didSave`	Performs authoritative compilation using on-disk content.
`textDocument/didClose`	`InterlisTextDocumentService#didClose`	Clears diagnostics and releases document state.
`textDocument/completion`	`InterlisTextDocumentService#completion`	Provides context-aware completions (triggered by `.` or `:`).
`textDocument/formatting`	`InterlisTextDocumentService#formatting`	Runs ili2c pretty printer for whole-document formatting.
`textDocument/onTypeFormatting`	`InterlisTextDocumentService#onTypeFormatting`	Auto-inserts INTERLIS templates after typing `=`.
`textDocument/definition`	`InterlisTextDocumentService#definition`	Resolves definitions across workspace & referenced models.
`textDocument/rename`	`InterlisTextDocumentService#rename` + `InterlisRenameProvider`	Applies validated renames across declarations and references.
`textDocument/documentSymbol`	`InterlisTextDocumentService#documentSymbol`	Builds outline nodes from the compiled AST.
`workspace/didChangeConfiguration`	`InterlisWorkspaceService#didChangeConfiguration`	Refreshes server-side model repository settings.

The VS Code extension maps these hooks to familiar IDE features such as the outline tree, problems panel, and rename refactorings.