feat(gui): UserTally editor

[dhanavanthesh]

Closes TODO.md line 46.

• Implement UserTally options/definition in GUI

---

The // TODO !! at simulationoptionsview.cpp:74 replaced with a full UserTallyView widget.

Tally management

• Add, remove, rename, duplicate from toolbar
• Duplicate produces collision-safe id: _copy, _copy2, ...
• Event picker: IonStop, IonExit, Vacancy, Replacement, CascadeComplete, BoundaryCrossing
• Disables during simulation run, reloads on revert

Bin variable table

• 14 variables in a dropdown with name + description
• [~] - linspace dialog per row: enter min, max, N, live edge preview
• [×] - removes that variable
• Non-monotonic edges turn the cell red

Live summary

• "2D tally: x × E (100 × 50 = 5000 bins)"
• Amber at 10 000 bins, red at 200 000
• Memory shown as ~40.0 KB / ~2.30 MB
• Warning text at 500 000 bins

Coordinate system

• "Use lab frame" checkbox hides origin/z-axis/xz-vector fields when not needed

Templates

• 6 presets: Depth Profile, Angular Distribution, Energy Spectrum, Implantation Map, Vacancy Depth Profile, Lateral Spread
• Preview shows x : 0 → 100 (100 bins) per variable
• If no tallies exist, one is created automatically before the dialog opens
• Template JSON cached after first parse

---

Also fixed a latent issue in OptionsModel to setData(idx, QVariant()) was silently reaching ojson::parse("") on every array edit from the GUI. Replaced with notifyDataChanged() across all call sites in materialsdefview.cpp and regionsview.cpp. Empty string guard added in parse_json::set_impl_. Container nodes marked non-editable in flags().