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/RunSetup.tsx

@@ -208,6 +208,23 @@ export function promptWithImages(text: string, images: PromptImage[]): string {
   return [text.trim(), ...images.map((i) => i.path)].filter(Boolean).join(" ");
 }
 
+const IMAGE_PATH = /^[^@].*\.(png|jpe?g|gif|webp)$/i;
+
+/** The prompt as pasted into a live pane: the text with every non-image file
+ *  in it (as `promptWithImages`), and the images' paths apart — each goes in
+ *  a paste of its own, the one shape `claude` turns into `[Image #n]` on every
+ *  platform (a Windows path inside a paste of text stayed a plain path). */
+export function promptForPane(
+  text: string,
+  images: PromptImage[]
+): { text: string; files: string[] } {
+  const isImage = (i: PromptImage) => IMAGE_PATH.test(i.path);
+  return {
+    text: promptWithImages(text, images.filter((i) => !isImage(i))),
+    files: images.filter(isImage).map((i) => i.path),
+  };
+}
+
 /** A plain-text paste longer than this is attached as `pasted-text.txt`. */
 export const PASTE_AS_FILE_CHARS = 5000;