feat(ui): enable drag-and-drop attachments and image previews in chat (#390)

* feat(BottomTerminalDock): add close button next to the fullscreen toggle in the dock

* style: replace hardcoded gradient with theme value in shine text variant

* fix(header): adapt instance button for desktop only

* refactor(chat): polish sticky turn UX and message action rows for better readability

Switch to stable sticky-only turn behavior and redesign user/assistant action controls (placement, hover rules, ordering, spacing, selection-safe clamp) to reduce visual noise and improve interaction flow.

* feat(chat/message): refactor buttons in messages footer

* feat: enhance image preview functionality in chat messages

- Added a new ImagePreviewDialog component to handle image previews with navigation support.
- Updated ToolOutputDialog to utilize the new ImagePreviewDialog for displaying images.
- Modified the ToolPopupContent type to include a gallery of images and an index for the current image.
- Removed the old inline image display logic from ToolOutputDialog.
- Improved file handling in the file store, including better MIME type guessing and handling of server paths.
- Introduced a new API endpoint for handling large session message payloads, allowing for better management of multi-file attachments.
- Updated the VSCode bridge to support session message requests with appropriate headers and body handling.

* feat(proxy): implement SSE forwarding and enhance generic API request handling

* feat(chat): support submitting only queued messages

* feat: add image preview transition state

* fix: default VSCode view to draft and fixed sessions list regression

packages/vscode/webview/api/bridge.ts

@@ -107,6 +107,15 @@ export async function proxyApiRequest(options: {
   return sendBridgeMessageWithOptions<ProxiedApiResponse>('api:proxy', options, { timeoutMs: 0 });
 }
 
+export async function proxySessionMessageRequest(options: {
+  path: string;
+  headers?: Record<string, string>;
+  bodyText: string;
+}): Promise<ProxiedApiResponse> {
+  // Keep parity with server-side direct forwarder: let extension host control timeout.
+  return sendBridgeMessageWithOptions<ProxiedApiResponse>('api:session:message', options, { timeoutMs: 0 });
+}
+
 export type ProxiedSseStartResponse = {
   status: number;
   headers: Record<string, string>;