feat: workspaces shell + cwd-lsp rename + mcp/settings/system-prompt features + app wiring

- workspaces: URL-driven conversation grouping (home listing at /, routing,
  store, http adapter, WorkspaceCard) wired into the App.svelte shell
- rename features/workspace -> features/cwd-lsp (the cwd/lsp status feature)
- new features: mcp (status view), settings (chat-limit field), system-prompt
  (prompt builder), all rendered via the generic surface host
- chat: store + ChatView updates
- tabs: tabs-store updates
- app wiring: ErrorModal (full-screen error surface), app/App.svelte + store.svelte

This commit makes HEAD typecheck clean for the first time: the prior HEAD
(c95cc77) imported features/settings from app/App.svelte but never committed
the feature, so only the full working tree was green.

1 files changed, 89 insertions, 0 deletions

diff --git a/src/features/settings/ui/ChatLimitField.test.ts b/src/features/settings/ui/ChatLimitField.test.ts
new file mode 100644
index 0000000..73bc449
--- /dev/null
+++ b/src/features/settings/ui/ChatLimitField.test.ts
@@ -0,0 +1,89 @@
+import { render, screen } from "@testing-library/svelte";
+import userEvent from "@testing-library/user-event";
+import { describe, expect, it } from "vitest";
+import type { ChatLimitSaveResult } from "../logic/view-model";
+import ChatLimitField from "./ChatLimitField.svelte";
+
+// A fake save that resolves ok with the value it was given.
+function fakeSave(): {
+	saves: number[];
+	last: number | null;
+	impl: (value: number) => Promise<ChatLimitSaveResult>;
+} {
+	const saves: number[] = [];
+	return {
+		saves,
+		last: null,
+		impl: async (value: number) => {
+			saves.push(value);
+			return { ok: true, chatLimit: value };
+		},
+	};
+}
+
+describe("ChatLimitField", () => {
+	it("seeds the input from the persisted limit and disables Set while unchanged", () => {
+		render(ChatLimitField, { props: { chatLimit: 256, save: fakeSave().impl } });
+		expect(screen.getByLabelText("Chat limit")).toHaveValue("256");
+		expect(screen.getByRole("button", { name: "Set" })).toBeDisabled();
+	});
+
+	it("enables Set when the typed value differs (regression: number-binding coercion)", async () => {
+		const user = userEvent.setup();
+		const save = fakeSave();
+		render(ChatLimitField, { props: { chatLimit: 256, save: save.impl } });
+
+		const input = screen.getByLabelText("Chat limit");
+		await user.clear(input);
+		await user.type(input, "10");
+
+		expect(screen.getByRole("button", { name: "Set" })).toBeEnabled();
+	});
+
+	it("keeps Set disabled for non-numeric input", async () => {
+		const user = userEvent.setup();
+		const save = fakeSave();
+		render(ChatLimitField, { props: { chatLimit: 256, save: save.impl } });
+
+		const input = screen.getByLabelText("Chat limit");
+		await user.clear(input);
+		await user.type(input, "abc");
+
+		expect(screen.getByRole("button", { name: "Set" })).toBeDisabled();
+	});
+
+	it("clicking Set calls save with the parsed value and shows the confirmation", async () => {
+		const user = userEvent.setup();
+		const save = fakeSave();
+		const { rerender } = render(ChatLimitField, {
+			props: { chatLimit: 256, save: save.impl },
+		});
+
+		const input = screen.getByLabelText("Chat limit");
+		await user.clear(input);
+		await user.type(input, "50");
+		await user.click(screen.getByRole("button", { name: "Set" }));
+
+		expect(save.saves).toEqual([50]);
+		// In the real app the reactive `chatLimit` prop updates to the saved value
+		// (the store sets it synchronously), which clears `dirty` and reveals the
+		// "Saved" badge. Rerender simulates that propagation.
+		rerender({ chatLimit: 50, save: save.impl });
+		expect(screen.getByText(/Saved/i)).toBeInTheDocument();
+	});
+
+	it("clamps a below-floor value when saving", async () => {
+		const user = userEvent.setup();
+		const save = fakeSave();
+		render(ChatLimitField, { props: { chatLimit: 256, save: save.impl } });
+
+		const input = screen.getByLabelText("Chat limit");
+		await user.clear(input);
+		await user.type(input, "5"); // clamps to MIN (10)
+		await user.click(screen.getByRole("button", { name: "Set" }));
+
+		// The save port receives the clamped value (the view-model clamps before save).
+		expect(save.saves).toEqual([10]);
+		expect(input).toHaveValue("10");
+	});
+});