New mind maps, flowcharts and architecture diagrams always started with
Chinese labels, whatever language the interface used.
- createDefaultDiagramDocument takes optional starter labels. Without
them it returns the existing Chinese starter unchanged, so the other
callers (tests, desktop sidecar checks) keep their output.
- The web client passes translated labels from new diagram.seed keys in
en-US, zh-CN, ja and pl.
- fitDefaultDiagramLabels sizes the nodes and lays the starter out again
only when a translated label needs more room than the default label it
replaces, so the Chinese starter keeps its tuned geometry. The helper is
loaded with the lazily loaded diagram editor, which keeps dagre out of
the workspace chunk; if that import fails the note is still created
with the starter geometry.