phase 1: copy Kindred-only files onto upstream/main (FreeCAD 1.2.0-dev)

Wholesale copy of all Kindred Create additions that don't conflict with
upstream FreeCAD code:

- kindred-icons/ (1444 Catppuccin Mocha SVG icon overrides)
- src/Mod/Create/ (Kindred Create workbench)
- src/Gui/ Kindred source files (FileOrigin, OriginManager,
  OriginSelectorWidget, CommandOrigin, BreadcrumbToolBar, EditingContext)
- src/Gui/Icons/ (Kindred branding and silo icons)
- src/Gui/PreferencePacks/KindredCreate/
- src/Gui/Stylesheets/ (KindredCreate.qss, images_dark-light/)
- package/ (rattler-build recipe)
- docs/ (architecture, guides, specifications)
- .gitea/ (CI workflows, issue templates)
- mods/silo, mods/ztools submodules
- .gitmodules (Kindred submodule URLs)
- resources/ (kindred-create.desktop, kindred-create.xml)
- banner-logo-light.png, CONTRIBUTING.md

docs/src/development/contributing.md

@@ -0,0 +1,52 @@
+# Contributing
+
+Kindred Create is maintained at [git.kindred-systems.com/kindred/create](https://git.kindred-systems.com/kindred/create). Contributions are submitted as pull requests against the `main` branch.
+
+## Getting started
+
+```bash
+git clone --recursive ssh://git@git.kindred-systems.com:2222/kindred/create.git
+cd create
+pixi run configure
+pixi run build
+pixi run freecad
+```
+
+See [Building from Source](../guide/building.md) for the full development setup.
+
+## Branch and PR workflow
+
+1. Create a feature branch from `main`:
+   ```bash
+   git checkout -b feat/my-feature main
+   ```
+2. Make your changes, commit with conventional commit messages (see below).
+3. Push and open a pull request against `main`.
+4. CI builds and tests run automatically on all PRs.
+
+## Commit messages
+
+Use [Conventional Commits](https://www.conventionalcommits.org/):
+
+| Prefix | Purpose |
+|--------|---------|
+| `feat:` | New feature |
+| `fix:` | Bug fix |
+| `chore:` | Maintenance, dependencies |
+| `docs:` | Documentation only |
+| `art:` | Icons, theme, visual assets |
+
+Scope is optional but encouraged:
+- `feat(ztools): add datum point creation mode`
+- `fix(gui): correct menu icon size on Wayland`
+- `chore: update silo submodule`
+
+## Reporting issues
+
+Report issues at the [issue tracker](https://git.kindred-systems.com/kindred/create/issues). When reporting:
+
+1. Note whether the issue involves Kindred Create additions (ztools, Silo, theme) or base FreeCAD
+2. Include version info from **Help > About FreeCAD > Copy to clipboard**
+3. Provide reproduction steps and attach example files (FCStd as ZIP) if applicable
+
+For base FreeCAD issues, also check the [FreeCAD issue tracker](https://github.com/FreeCAD/FreeCAD/issues).