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/__tests__/RunSetup.test.tsx

@@ -24,6 +24,7 @@ import {
   ModelPicker,
   PASTE_AS_FILE_CHARS,
   PromptEditor,
+  promptForPane,
   promptWithImages,
   type PromptImage,
 } from "../RunSetup";
@@ -586,3 +587,23 @@ describe("ModelMenu", () => {
     expect(onChange).toHaveBeenCalledWith("claude-sonnet-5-5");
   });
 });
+
+describe("promptForPane — images apart, every other file in the text", () => {
+  it("keeps @-mentions and other files in the text, and takes images out", () => {
+    // A Windows path inside a paste of text stayed a plain path in claude; a
+    // paste that is only the path becomes [Image #n].
+    const images: PromptImage[] = [
+      { path: "C:\\Users\\u\\.claude\\agenthub\\drops\\f326fc666d3bdd92-image.png", name: "image.png" },
+      { path: "/data/drops/0123456789abcdef-log.txt", name: "log.txt" },
+      { path: '@"/home/u/My Docs/a.PNG"', name: "a.PNG" },
+      { path: "/data/drops/0123456789abcdef.JPG", name: "b.jpg" },
+    ];
+    expect(promptForPane(" look ", images)).toEqual({
+      text: 'look /data/drops/0123456789abcdef-log.txt @"/home/u/My Docs/a.PNG"',
+      files: [
+        "C:\\Users\\u\\.claude\\agenthub\\drops\\f326fc666d3bdd92-image.png",
+        "/data/drops/0123456789abcdef.JPG",
+      ],
+    });
+  });
+});