Add Align cylinders tool for shaft-into-hole placement

[trailcode]

Summary

• Add Align cylinders (Mode::Shape_cyl_align, default J / mode.cyl_align): pick two cylindrical faces (first moves), coaxially align, drag insert depth along the shared axis, then bake like Move/Rotate.
• Geometry helpers cylinder_from_face and cyl_align_trsf in utl_geom; new Shp_cyl_align op with Options Flip direction and radius-mismatch log warning.
• Docs: usage.md, shape.md, gui.md, CHANGELOG [Unreleased]; hotkey default in res/ezycad_settings.json.

Closes #239

Test plan

• Desktop Release build of EzyCad
• Manual: add cylinder (rod) + body with hole of same diameter; J → pick rod face → pick hole face → drag depth → LMB/Enter bake; undo/redo
• Manual: pick hole first to move hole onto rod; Options Flip direction; Tab depth entry; Esc cancel during pick and during drag
• Manual: planar end face → "not cylindrical"; empty click → solid/face prompt; remappable hotkey in Settings
• Docs: Align cylinders section + Modeling hotkeys row; toolbar tooltip shows J

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Note

Medium Risk
New interactive transform that permanently changes solid geometry and frame/undo state; logic depends on cylindrical face detection and alignment math, but it follows the same patterns as existing move/rotate tools.

Overview
Adds Align cylinders (Mode::Shape_cyl_align, default J / mode.cyl_align): a one-shot transform for placing a shaft in a hole by picking two cylindrical faces, coaxially aligning the first body to the second, then dragging or Tab-typing insert depth along the shared axis. Flip direction in Options reverses axis sense; mismatched radii log a warning but still allow placement. Finalize bakes geometry like Move/Rotate via Shape_geom_delta undo.

New Shp_cyl_align and utl_geom helpers (cylinder_from_face, cyl_align_trsf) implement face detection and rigid alignment. GUI wiring covers toolbar, hotkeys, face selection mode, LMB pick/finalize, depth drag, Esc cancel, and undo history treats the mode like other interactive transforms. Occt_view::set_dynamic_highlight_enabled is exposed and turned off during depth drag to avoid stale hover highlights.

User docs (usage.md, shape.md, gui.md, CHANGELOG) and default gui.hotkeys are updated. Minor unrelated cleanup: main.cpp Python queue brace formatting.

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