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>

.gitignore

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+dist/
+node_modules/
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+*.tgz