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__/PaneChat.test.tsx

@@ -267,7 +267,7 @@ describe("PaneChat — model, effort and permission mode", () => {
     renderChat();
     fireEvent.click(screen.getByRole("button", { name: /Opus/ }));
     fireEvent.click(await screen.findByRole("menuitemradio", { name: /Sonnet/ }));
-    expect(submitToRun).toHaveBeenCalledWith("agenthub-lane-1", "/model sonnet");
+    expect(submitToRun).toHaveBeenCalledWith("agenthub-lane-1", "/model sonnet", []);
   });
 
   it("shows the mode the pane shows, and asks the server to step it", async () => {
@@ -430,7 +430,7 @@ describe("PaneChat — the unsent prompt", () => {
     expect(screen.getByPlaceholderText("Write a message…")).toHaveValue("half typed");
     expect(screen.getByText("a.ts")).toBeInTheDocument();
     fireEvent.click(screen.getByTestId("pane-chat-send"));
-    expect(submitToRun).toHaveBeenCalledWith("agenthub-lane-1", "half typed @src/a.ts");
+    expect(submitToRun).toHaveBeenCalledWith("agenthub-lane-1", "half typed @src/a.ts", []);
     await waitFor(() => expect(localStorage.getItem("agenthub.chat.draft.s1")).toBeNull());
   });
 
@@ -462,7 +462,8 @@ describe("PaneChat — the unsent prompt", () => {
     fireEvent.click(screen.getByTestId("pane-chat-send"));
     expect(submitToRun).toHaveBeenCalledWith(
       "agenthub-lane-1",
-      'read @"/home/u/My Docs/spec.md" @/home/u/b.ts'
+      'read @"/home/u/My Docs/spec.md" @/home/u/b.ts',
+      []
     );
   });
 
@@ -490,7 +491,7 @@ describe("PaneChat — the unsent prompt", () => {
     expect(box).toHaveValue("hello");
     confirmDialog.mockResolvedValueOnce(true);
     fireEvent.click(screen.getByTestId("pane-chat-send"));
-    await waitFor(() => expect(submitToRun).toHaveBeenCalledWith("agenthub-lane-1", "hello"));
+    await waitFor(() => expect(submitToRun).toHaveBeenCalledWith("agenthub-lane-1", "hello", []));
   });
 
   it("sends without asking once the session has started", async () => {
@@ -499,7 +500,7 @@ describe("PaneChat — the unsent prompt", () => {
     renderChat();
     fireEvent.change(screen.getByPlaceholderText("Write a message…"), { target: { value: "hi" } });
     fireEvent.click(screen.getByTestId("pane-chat-send"));
-    await waitFor(() => expect(submitToRun).toHaveBeenCalledWith("agenthub-lane-1", "hi"));
+    await waitFor(() => expect(submitToRun).toHaveBeenCalledWith("agenthub-lane-1", "hi", []));
     expect(confirmDialog).not.toHaveBeenCalled();
   });
 });