grid-layout-plus@2.0.0-beta.0

Major Changes

• 79aa5fa Thanks @qmhc! - Make the parent Layout the canonical source of GridItem geometry, constraints, interaction
  flags, and stacking order. The corresponding GridItem mirror props are deprecated, and internal
  component-ref fields have been replaced by the typed GridLayoutExpose command API.

• bb74b26 Thanks @qmhc! - Require external drop item factories, commit created items before emitting drop, and support controlled same-group cross-grid moves with rollback.

• #64 3966b6a Thanks @qmhc! - Adopt a controlled, immutable layout model. GridLayout now emits readonly update proposals and
  commits them only after the parent writes layout back. Use v-model:layout to persist changes
  from interactions and public commands.

• 865f5da Thanks @qmhc! - Stop injecting component styles from JavaScript bundles and publish them through the explicit grid-layout-plus/style.css entry for consumer-side CSS processing.

• 79aa5fa Thanks @qmhc! - Replace legacy layout configuration with the v2 contracts. Rename margin to gap, note that
  containerPadding now defaults to [0, 0], and replace verticalCompact, useCssTransforms, and
  transformScale with compactor and positionStrategy. Grouped grid, drag, resize, and drop
  configuration now merges beneath flat props.

• 79aa5fa Thanks @qmhc! - Enforce strict layout contracts for safe-integer geometry, unique item ids, valid constraints, and
  cloneable plain custom data. Layout algorithms no longer mutate their inputs, and invalid layouts
  now produce structured GridLayoutValidationError or rejected operation results.

Minor Changes

• 79aa5fa Thanks @qmhc! - Add useGridLayout, useResponsiveLayout, and useContainerWidth for headless layout state,
  interaction lifecycles, responsive breakpoint resolution, and container measurement. Responsive
  layouts can also be persisted through synchronized controlled models.

• 79aa5fa Thanks @qmhc! - Add GridBackground for rendering grid lines from inherited or explicit geometry, with configurable
  row count, color, and stroke width.

• 79aa5fa Thanks @qmhc! - Expand interaction workflows with typed drag and resize lifecycles, transactional layout commands,
  native and external drop handling, drag thresholds, bounded movement, overlap layering commands,
  and structured operation events.

• 79aa5fa Thanks @qmhc! - Add the Vue-free grid-layout-plus/core entry point with immutable layout helpers, normalization,
  compactors, positioning strategies, geometry conversion, structured errors, and public types.

• 79aa5fa Thanks @qmhc! - Add configurable compaction, collision, and positioning strategies, including horizontal, disabled,
  and indexed compactors; push, prevent, and overlap collision modes; and absolute or scaled
  positioning.

• 853f149 Thanks @qmhc! - Add opt-in content-driven item heights with shared observation, controlled layout proposals,
  per-item overrides, collision handling, and width-only pointer resizing.

• cf42ee2 Thanks @qmhc! - Support configurable resize handles on every edge and corner, with per-item overrides and scoped
  slots for custom handle visuals. Keep the active item anchored under the pointer while the
  placeholder and surrounding items preview the terminal compacted layout.