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/overlays/alert-dialog/index.ts

@@ -0,0 +1,21 @@
+export { DialogDescription as AlertDialogDescription, DialogOverlay as AlertDialogOverlay, DialogPortal as AlertDialogPortal, DialogTitle as AlertDialogTitle, DialogTrigger as AlertDialogTrigger } from '../dialog';
+export { default as AlertDialogAction } from './AlertDialogAction.vue';
+export { default as AlertDialogCancel } from './AlertDialogCancel.vue';
+export { default as AlertDialogContent } from './AlertDialogContent.vue';
+
+export { default as AlertDialogRoot } from './AlertDialogRoot.vue';
+
+export { useAlertDialogContentContext } from './context';
+
+export type {
+  DialogDescriptionProps as AlertDialogDescriptionProps,
+  DialogOverlayProps as AlertDialogOverlayProps,
+  DialogPortalProps as AlertDialogPortalProps,
+  DialogTitleProps as AlertDialogTitleProps,
+  DialogTriggerProps as AlertDialogTriggerProps,
+} from '../dialog';
+export type { AlertDialogContentContext } from './context';
+export type { AlertDialogActionProps } from './AlertDialogAction.vue';
+export type { AlertDialogCancelProps } from './AlertDialogCancel.vue';
+export type { AlertDialogContentEmits, AlertDialogContentProps } from './AlertDialogContent.vue';
+export type { AlertDialogRootEmits, AlertDialogRootProps } from './AlertDialogRoot.vue';