Sync the agentfabric dialect and the @agentscript/language APIs it
depends on from the internal module-agentscript repo, so the build and
test suite pass in op-agentscript.

- Add agentfabric compiler and graph-extraction modules, lint rules, and
  tests carried over from module-agentscript.
- Extend @agentscript/language with the graph field markers the dialect
  needs: transitionContainer, predicateField, outputNameField, and
  displayLabelField (core/types.ts FieldMetadata flags + field-builder
  methods). Export isAstNodeLike and the Range type.
- Update getValueCompletions to the AST-aware signature and add
  walkParentsToSchemaContext plus CompletionCandidate.insertText; thread
  cycle detection through scope.ts walkers; update the lsp caller.
- Mark agentscript-dialect baseSubagentFields.label as displayLabelField
  so orchestrator nodes (cloned from SubagentBlock) surface their label
  in the extracted graph.