Initial commit: kanban-elements-ui library

Angular 19 component library for kanban boards:
- kb-board: main board with toolbar, swimlanes, and pipeline view
- kb-column: columns with WIP limits, collapse, and drag reorder
- kb-card: draggable cards with labels, assignees, and priorities
- kb-swimlane: horizontal grouping with collapsible rows
- kb-toolbar: search, sort, filter, and view toggle
- kb-quick-add: inline card creation
- kb-wip-indicator: WIP limit status display
- kb-card-def / kb-column-header-def: custom template directives

Includes signal-based services (board, drag, filter), SCSS design
tokens with dark mode, and full TypeScript type definitions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ng-package.json

@@ -0,0 +1,12 @@
+{
+  "$schema": "node_modules/ng-packagr/ng-package.schema.json",
+  "lib": {
+    "entryFile": "src/index.ts",
+    "styleIncludePaths": ["src/styles"]
+  },
+  "dest": "dist",
+  "deleteDestPath": true,
+  "assets": [
+    "src/styles/**/*.scss"
+  ]
+}