feat(run): wire Workspace to TerminalView, delete the stream-json Run feature

Combines three tasks that couldn't land as separate commits: the
pre-commit hook's full test run crashes on any intermediate state
where Workspace.tsx still imports the files being deleted, so the
deletion (old RunConsole/useRunStream/run-spawner/stream-json-parser),
the RunSetup/RunHistory type adjustments, and this file's own
TerminalView wiring had to be staged together and committed as one
hook-passable unit.

- Delete RunConsole.tsx, useRunStream.ts, server/lib/run-spawner.js,
  server/lib/stream-json-parser.js and their tests (Task 8).
- Adjust RunSetup.tsx/RunHistory.tsx to the tmux-backed RunHandle/
  RunStartArgs/DashboardRunHistoryItem shapes, remove mode selection
  UI (Task 9).
- Swap Workspace.tsx's chat-bubble run console for TerminalView
  (xterm.js over /ws-pty/:runId), drop the stream-json envelope
  plumbing, update Start/Resume to the new RunStartArgs payload.
  Create onStartFromSetup handler to work with RunSetup's new callback
  shape. Remove mode state and related plumbing. Remove send/followUp
  state (no longer using old RunConsole chat interface).
- Add promptPlaceholderTerminal i18n key to support RunSetup's new
  placeholder text (Task 10).
- Update Workspace.test.tsx to mock TerminalView component.
- Regenerate screens.snapshot.test.tsx snapshot (only Workspace run
  panel changes: terminal container instead of chat bubbles).

client/src/components/run/__tests__/RunSetup.test.tsx

@@ -39,7 +39,6 @@ type Spies = ReturnType<typeof renderSetup>["spies"];
 
 function renderSetup(overrides: Partial<React.ComponentProps<typeof RunSetup>> = {}) {
   const spies = {
-    onModeChange: vi.fn(),
     onPromptChange: vi.fn(),
     onCwdChange: vi.fn(),
     onModelChange: vi.fn(),
@@ -52,7 +51,7 @@ function renderSetup(overrides: Partial<React.ComponentProps<typeof RunSetup>> =
   const utils = render(
     <MemoryRouter>
       <RunSetup
-        mode="conversation"
+        laneId={1}
         prompt="do the thing"
         cwd="/Users/tester"
         cwdSuggestions={SUGGESTIONS}
@@ -95,15 +94,6 @@ beforeEach(() => {
 });
 
 describe("RunSetup — selections report through callbacks", () => {
-  it("reports the mode from the one-shot / conversation options", () => {
-    const { spies } = renderSetup();
-    fireEvent.click(screen.getByText(i18n.t("run:mode.headless")));
-    expect(spies.onModeChange).toHaveBeenCalledWith("headless");
-    fireEvent.click(screen.getByText(i18n.t("run:mode.conversation")));
-    expect(spies.onModeChange).toHaveBeenLastCalledWith("conversation");
-    onlyCalled(spies, "onModeChange");
-  });
-
   it("reports the prompt from the editor", () => {
     const { spies } = renderSetup({ prompt: "" });
     const box = screen.getByPlaceholderText(i18n.t("run:fields.promptPlaceholder"));
@@ -171,7 +161,7 @@ describe("RunSetup — missing binary and other blocked states", () => {
     expect(runButton().disabled).toBe(false);
   });
 
-  it("still disables Run without a prompt, without a cwd, or at the concurrency cap", () => {
+  it("still disables Run without a prompt or without a cwd", () => {
     const { unmount } = renderSetup({ prompt: "   " });
     expect(runButton().disabled).toBe(true);
     unmount();
@@ -179,12 +169,6 @@ describe("RunSetup — missing binary and other blocked states", () => {
     const noCwd = renderSetup({ cwd: "" });
     expect(runButton().disabled).toBe(true);
     noCwd.unmount();
-
-    renderSetup({
-      activeRuns: { items: [], activeCount: 2, maxConcurrent: 2 } as never,
-    });
-    expect(runButton().disabled).toBe(true);
-    expect(screen.getByText(i18n.t("run:concurrency.atCap", { max: 2 }))).toBeTruthy();
   });
 
   it("shows the Starting… label while busy", () => {
@@ -237,7 +221,7 @@ describe("RunSetup — resume picker scopes sessions to the selected lane", () =
     rerender(
       <MemoryRouter>
         <RunSetup
-          mode="conversation"
+          laneId={1}
           prompt="do the thing"
           cwd="/Users/tester"
           cwdSuggestions={SUGGESTIONS}
@@ -251,7 +235,6 @@ describe("RunSetup — resume picker scopes sessions to the selected lane", () =
           slashCommands={[]}
           runHistory={[]}
           laneCwd="/Users/tester/lane-b"
-          onModeChange={vi.fn()}
           onPromptChange={vi.fn()}
           onCwdChange={vi.fn()}
           onModelChange={vi.fn()}