UI improvements: shape delete, options scroll, inspection ortho

[trailcode]

Summary

• Shape List: right-click a shape name or the M button to Delete; click M for the material popup. Deletion goes through Occt_view::delete_shapes().
• Options pane: horizontal scrollbar and fixed-width tables so narrow layouts do not clip labels (e.g. Orthographic projection).
• Inspection (Normal) mode: Options -> Selection -> Orthographic projection toggles an orthographic camera, persisted as gui.inspection_orthographic.
• Docs: user guides and changelog updated for the above; UI verbosity is not documented (deferred for a future approach). Settings still exposes the control on this branch for experimentation.
• UI verbosity (gui.ui_verbosity, default 6): cumulative pane/help gating remains in code from earlier commits; treat as in-progress unless we strip it before merge.

Closes #108

Test plan

• Fresh defaults: app loads with familiar full UI; gui.inspection_orthographic false.
• Narrow Options pane: horizontal scrollbar appears; Orthographic projection label readable.
• Normal mode: orthographic checkbox toggles camera; survives restart.
• Shape List: right-click name -> Delete removes shape; right-click M -> Delete; click M opens material popup.
• Optional: Settings -> UI verbosity at 0 / 6 — panes and help tiers behave as implemented (undocumented).

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