feat(computer): SSH computer selection + status + workspace default (handoff #2)

Mirrors the cwd/workspace UI for the SSH-computer feature:

- New feature library src/features/computer/:
  - logic/view-model.ts (pure): viewComputer/viewComputerStatus/viewTestResult/
    summarizeComputers/formatHost/knownHostLabel + state->badge for the 4
    ComputerStatusResponse states + SaveComputer/LoadComputerStatus/
    TestComputer/LoadComputers ports. 20 view-model tests.
  - ui/ComputerField.svelte: per-conversation selector (dropdown +
    connection-status badge + Test-connection, polling the selected alias).
  - ui/ComputerSelect.svelte: reusable Local/computers dropdown, shared with
    the workspace default-computer control.
- AppStore: computerId state + refreshComputer (at every focus site, parallel
  to refreshCwd) + setComputer (PUT /conversations/:id/computer, null=clear) +
  global computers catalog (GET /computers on boot, like models) +
  computerStatus(alias) + testComputer(alias). chat.send UNCHANGED (resolved
  server-side like cwd).
- App.svelte: ComputerField in the Model sidebar view next to CwdField; adapted
  ports wrap the store.
- workspaces: setDefaultComputer on WorkspaceHttp+WorkspaceStore
  (PUT /workspaces/:id/default-computer); default-computer selector in
  WorkspaceCard (reuses ComputerSelect); router passes store.computers through.
- Re-mirrored .dispatch/transport-contract.reference.md (Computers section +
  ChatRequest.computerId); updated .dispatch/wire.reference.md (Computer/
  ComputerEntry/defaultComputerId + the provider-retry divergence note from
  handoff #1); GLOSSARY + backend-handoff.md (handoff #2, §2e).

Transparency invariant: the computer is USER-facing only (a tool-execution
target, never part of the model prompt); the agent never sees it.

Verify: 795/795 tests green; biome clean; vite build succeeds; 0 typecheck
errors from the computer feature. (11 pre-existing svelte-check errors remain
from the open §2d provider-retry divergence — backend feature/ssh-support
still lacks TurnProviderRetryEvent; not from this feature.)

1 files changed, 17 insertions, 6 deletions

diff --git a/src/features/workspaces/ui/WorkspaceCard.test.ts b/src/features/workspaces/ui/WorkspaceCard.test.ts
index 385856d..48b12b3 100644
--- a/src/features/workspaces/ui/WorkspaceCard.test.ts
+++ b/src/features/workspaces/ui/WorkspaceCard.test.ts
@@ -11,6 +11,7 @@ function fakeEntry(overrides: Partial<WorkspaceEntry> = {}): WorkspaceEntry {
 		id: "my-ws",
 		title: "My Workspace",
 		defaultCwd: null,
+		defaultComputerId: null,
 		createdAt: 1,
 		lastActivityAt: 2,
 		conversationCount: 3,
@@ -33,6 +34,12 @@ function fakeStore() {
 				value: fakeEntry({ id, defaultCwd }),
 			}),
 		),
+		setDefaultComputer: vi.fn(
+			async (id: string, computerId: string | null): Promise<WorkspaceResult<WorkspaceEntry>> => ({
+				ok: true,
+				value: fakeEntry({ id, defaultComputerId: computerId }),
+			}),
+		),
 		remove: vi.fn(
 			async (): Promise<WorkspaceResult<{ closedCount: number }>> => ({
 				ok: true,
@@ -47,7 +54,7 @@ describe("WorkspaceCard", () => {
 		const store = fakeStore() as unknown as WorkspaceStore;
 		const onNavigate = vi.fn();
 		render(WorkspaceCard, {
-			props: { ws: fakeEntry(), store, onNavigate },
+			props: { ws: fakeEntry(), store, onNavigate, computers: [] },
 		});
 		expect(screen.getByText("My Workspace")).toBeInTheDocument();
 		expect(screen.getByText("/my-ws")).toBeInTheDocument();
@@ -57,7 +64,9 @@ describe("WorkspaceCard", () => {
 	it("double-clicking the title reveals an edit input", async () => {
 		const user = userEvent.setup();
 		const store = fakeStore() as unknown as WorkspaceStore;
-		render(WorkspaceCard, { props: { ws: fakeEntry(), store, onNavigate: vi.fn() } });
+		render(WorkspaceCard, {
+			props: { ws: fakeEntry(), store, onNavigate: vi.fn(), computers: [] },
+		});
 
 		await user.dblClick(screen.getByText("My Workspace"));
 		expect(screen.getByLabelText("Workspace title")).toHaveValue("My Workspace");
@@ -66,7 +75,9 @@ describe("WorkspaceCard", () => {
 	it("renames via the store on Enter", async () => {
 		const user = userEvent.setup();
 		const store = fakeStore() as unknown as WorkspaceStore;
-		render(WorkspaceCard, { props: { ws: fakeEntry(), store, onNavigate: vi.fn() } });
+		render(WorkspaceCard, {
+			props: { ws: fakeEntry(), store, onNavigate: vi.fn(), computers: [] },
+		});
 
 		await user.dblClick(screen.getByText("My Workspace"));
 		const input = screen.getByLabelText("Workspace title");
@@ -80,7 +91,7 @@ describe("WorkspaceCard", () => {
 		const user = userEvent.setup();
 		const store = fakeStore() as unknown as WorkspaceStore;
 		render(WorkspaceCard, {
-			props: { ws: fakeEntry({ defaultCwd: "/old" }), store, onNavigate: vi.fn() },
+			props: { ws: fakeEntry({ defaultCwd: "/old" }), store, onNavigate: vi.fn(), computers: [] },
 		});
 
 		const input = screen.getByLabelText("Default working directory");
@@ -99,7 +110,7 @@ describe("WorkspaceCard", () => {
 		const user = userEvent.setup();
 		const store = fakeStore() as unknown as WorkspaceStore;
 		render(WorkspaceCard, {
-			props: { ws: fakeEntry({ defaultCwd: "/old" }), store, onNavigate: vi.fn() },
+			props: { ws: fakeEntry({ defaultCwd: "/old" }), store, onNavigate: vi.fn(), computers: [] },
 		});
 
 		const input = screen.getByLabelText("Default working directory");
@@ -113,7 +124,7 @@ describe("WorkspaceCard", () => {
 		const user = userEvent.setup();
 		const store = fakeStore() as unknown as WorkspaceStore;
 		const onNavigate = vi.fn();
-		render(WorkspaceCard, { props: { ws: fakeEntry(), store, onNavigate } });
+		render(WorkspaceCard, { props: { ws: fakeEntry(), store, onNavigate, computers: [] } });
 
 		await user.click(screen.getByRole("link", { name: "Open" }));
 		expect(onNavigate).toHaveBeenCalledWith("/my-ws");