feat(python-notebook-migration, frontend): add AI-generate-workflow modal, panel host, and LLM loading spinner

[zyratlo]

What changes were proposed in this PR?

Adds the user facing entry point for the Python notebook to Texera workflow migration tool: an "AI generate workflow" modal in the workspace menu, a workspace loading overlay with an elapsed time stopwatch shown while the LLM converts, auto layout of the generated workflow, and the <texera-jupyter-notebook-panel> host that embeds the iframe panel component from #5271.

Menu toolbar (menu.component.{ts,html,scss})

• Two buttons, both gated on the pythonNotebookMigrationEnabled config flag:
  • "AI generate workflow" (robot icon), also gated on workflow modifiability, opens the import modal.
  • "Expand Jupyter notebook" (Jupyter logo), shown only when the current workflow has a stored notebook (jupyterNotebookExists$), reopens the panel.
• openImportNotebookModal() opens an NzModalService modal to upload a .ipynb and pick a LiteLLM model.
  • Models load via notebookMigrationService.getAvailableModels(), with a loading state and a "no models available" state on fetch failure.
  • Both the file and the model are required before submit.
  • A warning banner states that generating overwrites the current workflow. On submit, a confirmation dialog appears only when the current workflow already has content (operators or comment boxes).
• onClickImportNotebook(file, model) runs the generation:
  • validates the .ipynb extension, then emits setWaitingForLLM(true) to show the overlay
  • parses the notebook and tags each cell with a metadata.uuid
  • calls sendToAIGenerateWorkflow(...) to get the generated workflow content and the cell to operator mapping
  • always overwrites the current workflow by reusing its wid so persistWorkflow(...) updates that row in place (a never saved workflow becomes a new row), which avoids leaving a duplicate "Untitled workflow"
  • persists the notebook and mapping via storeNotebookAndMapping(...)
  • reloads the workflow onto the live canvas and runs auto layout on the generated operators
  • shows the panel: when the wid is unchanged it sends the notebook and opens the panel directly; when a new row was created it points the URL at the generated workflow so JupyterPanelService.init() sends the notebook and opens the panel (avoids a double "sent to Jupyter" toast)
  • clears the overlay at every terminal state, including file read errors, parse failures, invalid notebooks, and LLM errors

Workspace (workspace.component.{ts,html,scss})

• Hosts <texera-jupyter-notebook-panel> (component landed in feat(python-notebook-migration, frontend): add Jupyter notebook iframe panel component #5271, now on main).
• Adds a loading overlay driven by the menu's setWaitingForLLM output, with an mm:ss elapsed time stopwatch. The interval is cleared on component destroy.

Assets

• jupyter-logo.svg: icon for the expand button.
• tool_popup_diagram.png: diagram shown at the top of the modal.

Tests

• Unit specs for the import flow (modal wiring, upload guard, model required, overwrite behavior, warning and confirm, error paths) and the workspace loading timer.

Any related issues, documentation, discussions?

Closes #4427
Parent issue #4301

How was this PR tested?

npx ng test for the menu and workspace specs. Manual end to end on a branch with the dependency PRs present: enabled the flag, opened the workspace menu, clicked AI generate workflow, picked a sample .ipynb and a LiteLLM model (auth is via the user's Texera JWT, no API key input), confirmed the overwrite prompt, and watched the stopwatch while the conversion ran. The generated workflow appeared in the editor with PythonUDFV2 operators auto laid out, the panel opened with the notebook in the embedded JupyterLab, clicking an operator scrolled its notebook cell into view, and clicking a cell highlighted its operators.

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

Generated-by: Claude Code (Claude Opus 4.8)

[codecov-commenter]

Codecov Report

❌ Patch coverage is 58.56354% with 75 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.37%. Comparing base (0f7a426) to head (bb929a8).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...c/app/workspace/component/menu/menu.component.html	18.18%	45 Missing ⚠️
...src/app/workspace/component/menu/menu.component.ts	79.56%	14 Missing and 5 partials ⚠️
...c/app/workspace/component/workspace.component.html	0.00%	11 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #5273      +/-   ##
============================================
- Coverage     80.47%   80.37%   -0.10%     
  Complexity     3875     3875              
============================================
  Files          1162     1162              
  Lines         46264    46447     +183     
  Branches       5153     5170      +17     
============================================
+ Hits          37230    37334     +104     
- Misses         7375     7448      +73     
- Partials       1659     1665       +6     

Flag	Coverage Δ		*Carryforward flag
access-control-service	70.00% <ø> (ø)		Carriedforward from f44d5cb
agent-service	77.42% <ø> (ø)		Carriedforward from f44d5cb
amber	75.30% <ø> (ø)		Carriedforward from f44d5cb
computing-unit-managing-service	20.49% <ø> (ø)		Carriedforward from f44d5cb
config-service	65.97% <ø> (ø)		Carriedforward from f44d5cb
file-service	66.80% <ø> (ø)		Carriedforward from f44d5cb
frontend	82.99% <58.56%> (-0.24%)	⬇️
notebook-migration-service	78.89% <ø> (ø)		Carriedforward from f44d5cb
pyamber	97.36% <ø> (ø)		Carriedforward from f44d5cb
workflow-compiling-service	26.31% <ø> (ø)		Carriedforward from f44d5cb

*This pull request uses carry forward flags. Click here to find out more.

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