Add SendCutSend Presets workbench

[rfaircl2]

Add SendCutSend Presets workbench

Summary

Adds a companion FreeCAD workbench / Mod, SendCutSendPresets, that applies SendCutSend public bend-calculator parameters (and user custom presets) to SheetMetal flanges and Unfold material sheets.

Motivation

Garage / job-shop users often copy bend radius and K-factor from SendCutSend by hand. This packages that table, applies it to SheetMetal features, creates Unfold-compatible material definition sheets, and syncs Unfold display properties — including when Unfold is created after Apply.

What’s included

• Workbench SendCutSend (SCS library + unified Bend Presets for testing)
• Runtime injection of Bend Presets (SCS + Custom) into the SheetMetal toolbar (no SheetMetal source changes)
• data/sendcutsend_bends.json snapshot from the public calculator (2026-09-05)
• Unfold K / Material Sheet sync + pending Apply-before-Unfold observer
• MIT license, package.xml for Addon Manager

Non-goals

• Not an official SendCutSend product
• Does not fork or patch SheetMetal sources
• Bend table may drift when SendCutSend updates — document refresh path in README

Test plan

• Fresh FreeCAD 1.1 install + SheetMetal; copy Mod; restart
• SheetMetal toolbar shows Bend Presets; open dialog; switch SCS ↔ My custom
• Apply all on Body with bends; radius/K update; min-flange warn if under min
• Material sheet appears; Unfold uses sheet; Data panel KFactor synced
• Apply all before Unfold; create Unfold; auto-sync runs (Report: Auto-synced…)
• Custom save → %APPDATA%/FreeCAD/SendCutSendPresets/custom_bends.json; reload survives Mod replace

Install path for reviewers

Lives at src/Mod/SendCutSendPresets/ in this VibeCAD tree (CMake add_subdirectory hooked). For stock FreeCAD, the same folder can still be copied into FreeCAD/Mod/.

Smoke / tests

cd src/Mod/SendCutSendPresets
python -m unittest tests.test_smoke -v

GUI / FreeCADCmd checklist: see SMOKE.md in the Mod.

AI-TDD: unit tests cover bend JSON + naming + min-flange rule without FreeCAD GUI. SheetMetal Apply/Unfold is manual/FreeCADCmd smoke (documented in SMOKE.md) because it requires SheetMetal + Qt.

CMake

Add to src/Mod/CMakeLists.txt:

add_subdirectory(SendCutSendPresets)

Mod provides its own CMakeLists.txt (installs Python sources, data, icons, tests).