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/canvas/flow/FlowViewport.vue

@@ -0,0 +1,52 @@
+<script lang="ts">
+import type { PrimitiveProps } from '../../internal/primitive';
+
+/**
+ * The single transformed layer. Every node and the edge `<svg>` live inside it,
+ * so pan/zoom is one GPU-composited `transform` rather than a per-element
+ * restyle. `transform-origin:0 0` is required — the coordinate formulas assume
+ * top-left scaling. `will-change:transform` is toggled on ONLY while interacting
+ * (never permanently): a pinned hint locks the compositor's raster scale, so the
+ * cached texture is GPU-upscaled and the graph blurs at high zoom — toggling it
+ * lets the layer re-rasterise crisply once motion settles (see
+ * `useInteractionState`). Mirrors `FlowNode`'s per-node drag toggle.
+ */
+export interface FlowViewportProps extends PrimitiveProps {}
+</script>
+
+<script setup lang="ts">
+import { computed } from 'vue';
+import { useForwardExpose } from '@robonen/vue';
+import { Primitive } from '../../internal/primitive';
+import { useFlowContext } from './context';
+
+const { as = 'div' } = defineProps<FlowViewportProps>();
+
+const ctx = useFlowContext();
+const { forwardRef } = useForwardExpose();
+
+const transform = computed(() => {
+  const vp = ctx.viewport.value;
+  return `translate(${vp.x}px, ${vp.y}px) scale(${vp.zoom})`;
+});
+</script>
+
+<template>
+  <Primitive
+    :ref="forwardRef"
+    :as="as"
+    data-flow-viewport=""
+    :style="{
+      position: 'absolute',
+      top: '0',
+      left: '0',
+      width: '100%',
+      height: '100%',
+      transformOrigin: '0 0',
+      transform,
+      willChange: ctx.isInteracting.value ? 'transform' : undefined,
+    }"
+  >
+    <slot />
+  </Primitive>
+</template>