Several quality improvements including top and bottom bus bar, seperate downloads for bus bars and a sharable configuration link

Co-authored-by: Copilot <copilot@github.com>

README.md

@@ -32,15 +32,46 @@ Live at https://generate.waak.me/
 
 ## Running it
 
-Any static file server will work. The project ships an OpenCascade WASM build under `vendor/`.
+This project now uses a Node-managed Vite workflow.
 
 ```bash
-python -m http.server 8000
-# or
-npx serve .
+npm install
+npm run dev
 ```
 
-Then open `http://localhost:8000`.
+Then open the URL printed by Vite (typically `http://localhost:5173`).
+
+Production build and preview:
+
+```bash
+npm run build
+npm run preview
+```
+
+The OpenCascade runtime files stay in `vendor/` and are resolved automatically in both dev and preview builds.
+
+## Shareable URL configuration
+
+All UI parameters are encoded into the URL hash so a link can reproduce the same setup.
+
+- Format: `#config=<payload>_<checksum>`
+- Payload: Base64URL-encoded JSON
+- Checksum: first 16 hex chars of SHA-256 over the raw JSON payload
+- Schema version: `v` field in the payload enables future migrations
+
+Included in the shared config:
+
+- Pack mode (`sp` or `mm`) and dimensions (`series`, `parallel`, `xDim`, `yDim`)
+- Cell and holder parameters (`cellSize`, `layoutType`, `spacing`, `height`, `coverThickness`, `ledgeWidth`, `roundedCorners`)
+- BMS settings (`bmsHolesType`, `bmsHoleDiameter`, `tabWidth`, `tabDepth`)
+- Busbar export format and full busbar list (`id`, `name`, `color`, `thickness`, `cellIndices`, `activeId`)
+
+Behavior notes:
+
+- URL hash updates are debounced while editing.
+- If payload, checksum, or schema version is invalid, the app rejects the shared config entirely and continues with defaults.
+- The checksum protects integrity against typos and tampering, but does not encrypt data.
+- Use the **Copy Share URL** button to copy a current, checksum-valid link.
 
 ## Project layout
 
@@ -69,7 +100,7 @@ vendor/
 
 ## Tech
 
-- Vanilla ES modules, no build step.
+- Vanilla ES modules with Vite dev/build tooling.
 - OpenCascade WASM for CAD operations and STEP export.
 - HTML5 Canvas 2D for the preview with DPR scaling and pan or pinch zoom.
 - DXF is hand rolled AutoCAD R12 so it opens cleanly in LightBurn, Fusion, and the usual suspects.