feat(web): align attachment display with DeepSeek Chat via ui-attachment atoms

Single-click original preview in the composer rail and chat history; remove
control inside the thumbnail, revealed on hover/focus (always on touch);
hidden-scrollbar rail overflow paged by edge arrows with wheel panning and
end-reveal on add; image-intake rejections and prompt failures announce as a
transient top-center toast instead of inline strips.

The attachment atoms move to a new zero-cordis package
@deepseek-ai/dsh-client-ui-attachment (rail, message gallery, lightbox),
seeded as a platform module; the toast is a ui-primitives atom. Strings
arrive as label props bridged from the conversation dictionary.

packages/client/web/package.json

@@ -29,6 +29,7 @@
   "dependencies": {
     "@deepseek-ai/dsh-client-modules": "workspace:^",
     "@deepseek-ai/dsh-client-schema-form": "workspace:^",
+    "@deepseek-ai/dsh-client-ui-attachment": "workspace:^",
     "@deepseek-ai/dsh-client-ui-primitives": "workspace:^",
     "@deepseek-ai/dsh-client-ui-slots": "workspace:^",
     "@deepseek-ai/dsh-client-ui-theme": "workspace:^",

packages/client/web/src/platform.ts

@@ -10,6 +10,7 @@ export const PLATFORM_MODULES = [
   '@deepseek-ai/dsh-client-ui-slots',
   '@deepseek-ai/dsh-client-web-react',
   '@deepseek-ai/dsh-client-ui-primitives',
+  '@deepseek-ai/dsh-client-ui-attachment',
   '@deepseek-ai/dsh-client-schema-form',
 ] as const
 

packages/client/web/src/seed.ts

@@ -14,6 +14,7 @@ import * as Cordis from '@deepseek-ai/cordis'
 import * as UiSlots from '@deepseek-ai/dsh-client-ui-slots'
 import * as WebReact from '@deepseek-ai/dsh-client-web-react'
 import * as UiPrimitives from '@deepseek-ai/dsh-client-ui-primitives'
+import * as UiAttachment from '@deepseek-ai/dsh-client-ui-attachment'
 import * as SchemaForm from '@deepseek-ai/dsh-client-schema-form'
 import type { PlatformModule } from './platform.ts'
 
@@ -34,6 +35,7 @@ export function getStaticModules(): Record<string, unknown> {
     '@deepseek-ai/dsh-client-ui-slots': UiSlots,
     '@deepseek-ai/dsh-client-web-react': WebReact,
     '@deepseek-ai/dsh-client-ui-primitives': UiPrimitives,
+    '@deepseek-ai/dsh-client-ui-attachment': UiAttachment,
     '@deepseek-ai/dsh-client-schema-form': SchemaForm,
   } satisfies Record<PlatformModule, unknown>
 }

packages/client/web/tsconfig.json

@@ -20,6 +20,9 @@
     {
       "path": "../ui-slots"
     },
+    {
+      "path": "../ui-attachment"
+    },
     {
       "path": "../ui-primitives"
     },