feat(vision): image paste + transcript image rendering + vision badge

Vision & vision-handoff frontend (consumes the backend's additive
[email protected] / [email protected] image types — no version bump).

Contracts mirrored:
- .dispatch/wire.reference.md: ImageChunk added to the Chunk union +
  ImageChunk/ImageInput interfaces.
- .dispatch/transport-contract.reference.md: ChatRequest.images,
  ModelMetadata.vision, + ImageChunk/ImageInput re-exports.

Core (core/chunks):
- conformance: assertChunkExhaustive handles the new 'image' variant
  (the guard caught it — its purpose).
- appendUserMessage(state, text, images?) echoes a [text, image, ...]
  user run; the user-message event dedup scans the trailing user run
  (not just the last chunk) so an image-bearing echo doesn't duplicate
  the text; applyHistory's during-gen dedup matches a multi-chunk echo
  by content equality (chunkContentEquals + trailingRun helpers).

UI:
- ChatView renders user 'image' chunks as lazy <img> bubbles; a
  non-vision model's persisted [image, analysis-text] both render.
  read_image tool renders generically (no special-casing).
- Composer: clipboard paste / file picker / drag-drop of images ->
  base64 data URLs, thumbnail previews with remove, forwarded on
  chat.send (omitted when none). Image-only sends allowed; steering
  (chat.queue) never forwards images.
- ModelSelector: vision badge (isVisionModel) marks vision-capable
  models; indicator shows native-vision vs vision-handoff hint.

Store wiring: ChatStore.send + AppStore.send + App.svelte handleSend
thread images through; chat.send still omits cwd (only images added).

Verification: svelte-check 0/0; vitest 901/901 (run twice, +34 new);
biome clean; vite build OK. See backend-handoff.md §2j.

Not merged or pushed.

1 files changed, 9 insertions, 4 deletions

diff --git a/src/app/App.svelte b/src/app/App.svelte
index 09be947..f240a06 100644
--- a/src/app/App.svelte
+++ b/src/app/App.svelte
@@ -1,5 +1,5 @@
 <script lang="ts">
-	import type { ReasoningEffort } from "@dispatch/transport-contract";
+	import type { ImageInput, ReasoningEffort } from "@dispatch/transport-contract";
 	import type { InvokeMessage } from "@dispatch/ui-contract";
 	import { tick } from "svelte";
 	import Table from "../components/Table.svelte";
@@ -241,8 +241,8 @@
 		store.invoke(msg.surfaceId, msg.actionId, msg.payload);
 	}
 
-	function handleSend(text: string) {
-		store.send(text);
+	function handleSend(text: string, images?: readonly ImageInput[]): void {
+		store.send(text, images);
 	}
 
 	function handleQueue(text: string) {
@@ -587,7 +587,12 @@
 {#snippet viewContent(kind: string)}
 	{#if kind === "model"}
 		<div class="flex flex-col gap-3">
-			<ModelSelector models={store.models} selected={store.activeModel} onSelect={handleSelectModel} />
+			<ModelSelector
+			models={store.models}
+			selected={store.activeModel}
+			onSelect={handleSelectModel}
+			modelInfo={store.modelInfo}
+		/>
 			<!-- Keyed on the workspace conversation (active tab OR draft) so the inputs
 			     re-mount per conversation — incl. switching between drafts — and can't
 			     bleed across tabs. Editable for a draft too (cwd + effort apply from turn 1). -->