fix(wunderbaum): node classes as a Set and no_events for set_active_node

[LukasGold]

Changes

• wunderbaum.vue updateNode: convert classes to a Set through a new toClassSet() helper. An empty string or None clears the classes.
• wunderbaum.vue setActiveNode and the setActiveNode action dispatch: forward noEvents to node.setActive().
• wunderbaum.py set_active_node: new no_events: bool = False parameter.
• wunderbaum.vue getSerializableSource: emit classes as a space-separated string.
• vue/dist/wunderbaum_vue.mjs: rebuilt bundle.
• New tests/panels/wunderbaum/test_wunderbaum_node_classes.py with 9 Playwright tests.
• docs/panels/wunderbaum.md: one sentence on no_events.

Rationale

• Wunderbaum stores node.classes as Set<string> | null and renders it with classList.add(...node.classes). updateNode assigned the raw string, so "highlighted" became 11 one-letter classes and "highlighted urgent" threw InvalidCharacterError.
• set_active_node always fired activate. Two trees whose activate handlers mirror the active node into each other called each other without end.
• getSerializableSource put the Set into the payload. JSON.stringify encodes a Set as {}, so classes loaded from the source were lost on every sync back to Python.

Compatibility

• no_events defaults to False, so existing callers keep the old behaviour. The only caller in the repository, examples/usecases/wunderbaum_visnetwork.py#L419, is unchanged.
• addNode and the source loader were not affected: the library's node constructor already converts classes through setClass().

Testing

• pytest tests/panels/wunderbaum/test_wunderbaum_node_classes.py: 9 passed
• pytest tests/panels/wunderbaum/: 84 passed, 1 xfailed
• The new tests against the pre-fix code: 8 failed, 1 passed. The passing test covers the default activation path, which was not broken.
• pre-commit run on the changed files: passed

Not in this PR

• updateNodeSilent, used by batch_update and execute_step, ignores classes. This gap existed before this change.
• docs/apidocs/panelini/panelini.panels.wunderbaum.wunderbaum.md still shows the old set_active_node signature until the next autodoc2 docs build.

[github-actions]

Release preview

Merging this PR would release 1.0.1 (current: 1.0.0).

Changelog preview (truncated)

## v1.0.1 (2026-09-18)

### Bug Fixes

- **wunderbaum**: Correct node classes and add no_events to activation
  ([`d02ec44`](https://github.com/opensemanticworld/panelini/commit/d02ec44975fc83bb51b55e0f1b0e78a694e8becb))

### Documentation

- **wunderbaum**: Document no_events on set_active_node
  ([`9fc5794`](https://github.com/opensemanticworld/panelini/commit/9fc5794664f3dc750c4280c245fc921c69cbb9dc))

### Testing

- **wunderbaum**: Cover node classes and no_events activation
  ([`c6165aa`](https://github.com/opensemanticworld/panelini/commit/c6165aa7023ac8eb668384441a81274270a30f42))

- **wunderbaum**: State what the loop bound does and does not prove
  ([`d78eadb`](https://github.com/opensemanticworld/panelini/commit/d78eadb48f5fdc2fc1fd91ab757f3f03a79b4006))

_{Preview via python-semantic-release and conventional commits.}

[codecov]

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