perf: faster plugin updates, half-size first bundle, images from the chat attach on Windows

- Chat view: an attached image's path is pasted on its own after the text
  (promptForPane). claude turns a paste that is only an image path into
  [Image #n], but left a Windows path inside a paste of text as a plain path.
  Other files and @-mentions stay in the text as before.
- Plugin bootstrap: depsHash covers only what npm installs (no release
  version), so a version bump no longer reinstalls runtime deps; the client's
  installed tree is kept while its manifests are unchanged (no npm ci per
  update); the user-side build runs vite only (tsc -b cost ~25 s / ~900 MB);
  clientBuild is recorded only after a build that did not fail, so a failed
  one is retried; npm output goes to runtime/npm-install.log.
- Server: a port held by another program ends with a clear message and exit 1
  instead of an uncaught 'error' stack trace.
- Client: the onboarding wizard is lazy and rendered only before onboarding;
  usePrefersReducedMotion moved to hooks/ so PetSettings no longer pulls the
  Sagi chat/pane stack into the entry chunk (884 KB -> 431 KB, gzip 268 -> 133 KB).

client/src/components/run/PaneGrid.tsx

@@ -73,7 +73,7 @@ import { RunDot, type RunState } from "./ConsoleTabs";
 import { setSessionChat, useSessionChat } from "../../lib/chatUi";
 import { readChatDraft, writeChatDraft } from "../../lib/chatDraft";
 import { pasteToRun, takeRunInput } from "../../lib/panePaste";
-import { promptWithImages } from "./RunSetup";
+import { promptForPane } from "./RunSetup";
 
 export const PANE_DRAG_TYPE = "application/x-agenthub-pane";
 /** The slot being dragged: `dataTransfer` data cannot be read during dragover. */
@@ -246,8 +246,8 @@ const ITEM =
  *  the CLI's input box, without Enter. */
 export function showTerminal(runId: string, sessionId: string) {
   const draft = readChatDraft(sessionId);
-  const text = promptWithImages(draft.prompt, draft.images);
-  if (text && pasteToRun(runId, text)) writeChatDraft(sessionId, "", []);
+  const { text, files } = promptForPane(draft.prompt, draft.images);
+  if ((text || files.length) && pasteToRun(runId, text, files)) writeChatDraft(sessionId, "", []);
   setSessionChat(sessionId, false);
 }