feat(primitives): media-editor components, category reorg, perf + type cleanup

Reorganize components into category folders (forms/canvas/overlays/etc.); add the
media-editor headless family (timeline, curve-editor, waveform, crop, color
picker, etc.); apply perf fixes (O(1) collection lookups, plain-object drag
state, gesture-leak teardown, shallowRef color state, rect caching) and replace
source `any` with proper types.

vue/primitives/src/feedback/toast/ToastProvider.vue

@@ -0,0 +1,79 @@
+<script lang="ts">
+import type { SwipeDirection } from './context';
+
+/**
+ * Toast — a succinct, non-disruptive notification that appears in a corner of the
+ * screen and auto-dismisses after a timeout. Use it to confirm actions or surface
+ * background events without interrupting the user's flow.
+ *
+ * `ToastProvider` is the top-level wrapper that holds shared settings (label, default
+ * duration, swipe behaviour) and coordinates timer pausing across all toasts. Wrap
+ * your app (or the region that renders toasts) in a single provider, render one
+ * `ToastViewport` for placement, and mount a `ToastRoot` per notification.
+ */
+export interface ToastProviderProps {
+  /** Accessible label for the toast region. @default 'Notifications' */
+  label?: string;
+  /** Auto-dismiss duration in ms. Use `Infinity` to disable auto-dismiss. @default 5000 */
+  duration?: number;
+  /** Swipe direction that dismisses a toast. @default 'right' */
+  swipeDirection?: SwipeDirection;
+  /** Minimum swipe distance (px) before a dismiss gesture is recognised. @default 50 */
+  swipeThreshold?: number;
+  /** Disable swipe-to-dismiss gestures for every toast. @default false */
+  disableSwipe?: boolean;
+}
+</script>
+
+<script setup lang="ts">
+import { ref, shallowRef, toRef } from 'vue';
+
+import { useCollectionProvider } from '../../utilities/collection';
+import { provideToastProviderContext } from './context';
+import { TOAST_COLLECTION_KEY } from './shared';
+
+const {
+  label = 'Notifications',
+  duration = 5000,
+  swipeDirection = 'right',
+  swipeThreshold = 50,
+  disableSwipe = false,
+} = defineProps<ToastProviderProps>();
+
+if (typeof label === 'string' && label.trim() === '')
+  throw new Error('Invalid prop `label` supplied to `ToastProvider`. Expected a non-empty string.');
+
+const labelRef = toRef(() => label);
+const durationRef = toRef(() => duration);
+const swipeDirectionRef = toRef(() => swipeDirection);
+const swipeThresholdRef = toRef(() => swipeThreshold);
+const disableSwipeRef = toRef(() => disableSwipe);
+
+const toastCount = ref(0);
+const viewportRef = shallowRef<HTMLElement | undefined>(undefined);
+const isFocusedToastEscapeKeyDownRef = ref(false);
+const isClosePausedRef = ref(false);
+
+// Dedicated collection key so a nested collection provider (or another toast
+// provider) does not shadow this one for descendant toasts/viewports.
+useCollectionProvider(TOAST_COLLECTION_KEY);
+
+provideToastProviderContext({
+  label: labelRef,
+  duration: durationRef,
+  swipeDirection: swipeDirectionRef,
+  swipeThreshold: swipeThresholdRef,
+  disableSwipe: disableSwipeRef,
+  toastCount,
+  viewportRef,
+  onViewportChange: (el) => { viewportRef.value = el; },
+  onToastAdd: () => { toastCount.value++; },
+  onToastRemove: () => { toastCount.value--; },
+  isFocusedToastEscapeKeyDownRef,
+  isClosePausedRef,
+});
+</script>
+
+<template>
+  <slot />
+</template>