feat(python-notebook-migration): add Jupyter panel mapping highlight service

[zyratlo]

What changes were proposed in this PR?

Introduces JupyterPanelService carrying the bidirectional cell to operator highlight orchestration, and the workflow-editor hook that calls into it on operator click.

JupyterPanelService

• init() — subscribes to workflowMetaDataChanged() and is registered as an APP_BOOTSTRAP_LISTENER in app.module.ts so it starts on app bootstrap. On each workflow change: drops any stale mapping for the current workflow (inline
  deleteMapping("mapping_wid_" + currentWid)), then fetches the new workflow's stored notebook + mapping from the microservice, sends the notebook to JupyterLab, and pre-computes the highlight index.
• setIframeRef(iframe) — called by the panel component (lands in PR 5) once its iframe is in the DOM.
• onWorkflowComponentClick(cellUUID) — public entry called by the workflow-editor's operator-click handler. If the iframe is present and the cell-UUID is mapped to operators, sends a triggerCellClick postMessage to custom.js so the
  matching notebook cell scrolls into view and is highlighted.
• precomputeHighlightMapping (private) — single-pass build of a cellUUID → { components: opId[], edges: linkId[] } index from the stored mapping + the current graph's links. Lets handleNotebookMessage do an O(1) lookup per cell click.
• handleNotebookMessage (private) — window.addEventListener("message", ...) handler installed in the constructor. Verifies origin against notebookMigrationService.getJupyterURL() before dispatching highlightFromCell for cellClicked
  events.
• highlightFromCell (private) — issues the actual unhighlightOperators / unhighlightLinks + highlightOperators / highlightLinks calls against WorkflowActionService.
• fetchNotebookAndMapping (private) — POST /api/notebook-migration/fetch-notebook-and-mapping; sets the mapping cache and forwards the notebook to JupyterLab. Returns 1 if both succeeded, 0 otherwise (caught errors included).
  Currently exposed via (service as any).fetchNotebookAndMapping(...) in the spec.

Any related issues, documentation, discussions?

Closes #5053
Parent issue #4301

How was this PR tested?

New test file jupyter-panel.service.spec.ts is added alongside the main service file.

Was this PR authored or co-authored using generative AI tooling?

Generated-by: Claude Code (Claude Opus 4.7)