feat(python-notebook-migration, frontend): add Jupyter panel visibility surface and mini-map expand-panel button

[zyratlo]

What changes were proposed in this PR?

Adds the panel-visibility surface to JupyterPanelService (BehaviorSubject + four open/close/minimize methods) and the mini-map expand-panel button that drives openJupyterNotebookPanel.

jupyter-panel.service.ts amends:

• Restores BehaviorSubject to the rxjs import.
• Adds private jupyterNotebookPanelVisible = new BehaviorSubject<boolean>(false) and the public jupyterNotebookPanelVisible$ = this.jupyterNotebookPanelVisible.asObservable().
• Adds four if (!this.enabled) return;-gated methods:
  • openPanel(panelName: string) — flips visibility to true when panelName === "JupyterNotebookPanel". (The panelName string is the existing convention used elsewhere in the workspace's panel system.)
  • closeJupyterNotebookPanel() — flips visibility to false, then notebookMigrationService.deleteMapping("mapping_wid_" + workflowActionService.getWorkflow().wid).
  • minimizeJupyterNotebookPanel() — flips visibility to false.
  • openJupyterNotebookPanel() — checks notebookMigrationService.hasMapping(...); warns via notificationService.warning("No Jupyter notebook associated with this workflow.") and returns if the workflow has no cached mapping, otherwise flips visibility to true.
• Refactors init()'s subscribe handler
  • replaces the inlined deleteMapping placeholder with the actual this.closeJupyterNotebookPanel() call
  • re-adds the this.openJupyterNotebookPanel() auto-open after precomputeHighlightMapping().

jupyter-panel.service.spec.ts amends:

• Adds 5 enabled-flag visibility tests in a "Panel visibility" section:
  • openPanel then closeJupyterNotebookPanel round-trips the visibility stream
  • minimizeJupyterNotebookPanel flips to false
  • openJupyterNotebookPanel warns when no mapping is cached
  • openJupyterNotebookPanel flips to true when one is; openPanel only flips for the correct panel name.
• Adds 4 disabled-flag tests inside the existing when the feature flag is disabled describe block — one per gated method — asserting the short-circuit via observable / spy checks (no next() emission from the method itself, no
  deleteMapping call, no notification.warning).

Mini-map expand-panel button (mini-map.component.{ts,html,scss}, ~37 lines):

• New *ngIf="pythonNotebookMigrationEnabled"-gated button (icon expand-alt) at the top of the mini-map's button cluster.
• The component injects JupyterPanelService and GuiConfigService; the click handler calls jupyterPanelService.openJupyterNotebookPanel(). With the flag at its default false on main, the button doesn't render and the rest of the mini-map UI is unchanged.

Any related issues, documentation, discussions?

Closes #5264
Parent issue #4301

• Hard dependency: must be merged after migration-tool-mapping-highlighting feat(python-notebook-migration): add Jupyter panel mapping highlight service #5263

How was this PR tested?

jupyter-panel.service.spec.ts is amended with 5 more visibility cases and 4 more disabled-flag cases

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

Generated-by: Claude Code (Claude Opus 4.7)