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, 151 insertions, 0 deletions

diff --git a/src/app/ErrorModal.svelte b/src/app/ErrorModal.svelte
new file mode 100644
index 0000000..7fc09a6
--- /dev/null
+++ b/src/app/ErrorModal.svelte
@@ -0,0 +1,151 @@
+<script lang="ts">
+	/**
+	 * Full-screen error modal — surfaces critical errors that would otherwise be
+	 * silently swallowed (e.g. the cross-device tab-restore fetch failing). Shows
+	 * the full error text + stack trace in a scrollable `<pre>`, a Copy button
+	 * (clipboard), and an X to dismiss. Pure presentation: the error string and
+	 * dismiss callback are injected as props.
+	 */
+	let {
+		error,
+		onDismiss,
+	}: {
+		error: string;
+		onDismiss: () => void;
+	} = $props();
+
+	let copied = $state(false);
+	let copyTimer: ReturnType<typeof setTimeout> | undefined;
+
+	async function handleCopy(): Promise<void> {
+		try {
+			await navigator.clipboard.writeText(error);
+			copied = true;
+			clearTimeout(copyTimer);
+			copyTimer = setTimeout(() => {
+				copied = false;
+			}, 2000);
+		} catch {
+			// Clipboard API may be unavailable (non-secure context). Fallback:
+			// select the text so the user can Ctrl+C manually.
+			const pre = document.getElementById("error-modal-text");
+			if (pre !== null) {
+				const range = document.createRange();
+				range.selectNodeContents(pre);
+				const selection = window.getSelection();
+				selection?.removeAllRanges();
+				selection?.addRange(range);
+			}
+		}
+	}
+
+	function handleKeydown(event: KeyboardEvent): void {
+		if (event.key === "Escape") {
+			event.preventDefault();
+			onDismiss();
+		}
+	}
+</script>
+
+<svelte:window onkeydown={handleKeydown} />
+
+<!-- Full-screen overlay: fixed, high z-index, semi-transparent backdrop. -->
+<!-- svelte-ignore a11y_no_static_element_interactions -->
+<div
+	class="fixed inset-0 z-50 flex items-center justify-center bg-black/60 p-4"
+	role="dialog"
+	aria-modal="true"
+	aria-label="Error"
+>
+	<div class="flex max-h-[80vh] w-full max-w-2xl flex-col rounded-lg bg-base-100 shadow-xl">
+		<!-- Header -->
+		<div class="flex items-center justify-between border-b border-base-300 px-4 py-3">
+			<div class="flex items-center gap-2">
+				<svg
+					xmlns="http://www.w3.org/2000/svg"
+					fill="none"
+					viewBox="0 0 24 24"
+					stroke-width="2"
+					stroke="currentColor"
+					class="size-5 text-error"
+					aria-hidden="true"
+				>
+					<path
+						stroke-linecap="round"
+						stroke-linejoin="round"
+						d="M12 9v3.75m-9.303 3.376c-.866 1.5.217 3.374 1.948 3.374h14.71c1.73 0 2.813-1.874 1.948-3.374L13.949 3.378c-.866-1.5-3.032-1.5-3.898 0L2.697 16.126ZM12 15.75h.007v.008H12v-.008Z"
+					/>
+				</svg>
+				<h2 class="text-lg font-semibold text-error">Something went wrong</h2>
+			</div>
+			<button
+				type="button"
+				class="btn btn-ghost btn-sm btn-square"
+				aria-label="Dismiss error"
+				onclick={onDismiss}
+			>
+				<svg
+					xmlns="http://www.w3.org/2000/svg"
+					fill="none"
+					viewBox="0 0 24 24"
+					stroke-width="2"
+					stroke="currentColor"
+					class="size-5"
+					aria-hidden="true"
+				>
+					<path stroke-linecap="round" stroke-linejoin="round" d="M6 18 18 6M6 6l12 12" />
+				</svg>
+			</button>
+		</div>
+
+		<!-- Body: scrollable error text -->
+		<div class="overflow-auto p-4">
+			<pre
+				id="error-modal-text"
+				class="whitespace-pre-wrap break-words font-mono text-xs leading-relaxed opacity-80"
+			>{error}</pre>
+		</div>
+
+		<!-- Footer: copy button -->
+		<div class="flex items-center justify-between gap-2 border-t border-base-300 px-4 py-3">
+			<span class="text-xs opacity-50">Press Esc to dismiss</span>
+			<button
+				type="button"
+				class="btn btn-sm {copied ? 'btn-success' : 'btn-outline'}"
+				onclick={handleCopy}
+			>
+				{#if copied}
+					<svg
+						xmlns="http://www.w3.org/2000/svg"
+						fill="none"
+						viewBox="0 0 24 24"
+						stroke-width="2"
+						stroke="currentColor"
+						class="size-4"
+						aria-hidden="true"
+					>
+						<path stroke-linecap="round" stroke-linejoin="round" d="m4.5 12.75 6 6 9-13.5" />
+					</svg>
+					Copied
+				{:else}
+					<svg
+						xmlns="http://www.w3.org/2000/svg"
+						fill="none"
+						viewBox="0 0 24 24"
+						stroke-width="2"
+						stroke="currentColor"
+						class="size-4"
+						aria-hidden="true"
+					>
+						<path
+							stroke-linecap="round"
+							stroke-linejoin="round"
+							d="M15.75 17.25v3.375c0 .621-.504 1.125-1.125 1.125h-9.75a1.125 1.125 0 0 1-1.125-1.125V7.875c0-.621.504-1.125 1.125-1.125H6.75a9.06 9.06 0 0 1 1.5.124m7.5 10.376h3.375c.621 0 1.125-.504 1.125-1.125V11.25c0-4.46-3.243-8.161-7.5-8.876a9.06 9.06 0 0 0-1.5-.124H9.375c-.621 0-1.125.504-1.125 1.125v3.5m7.5 10.375H9.375a1.125 1.125 0 0 1-1.125-1.125v-9.25m18 3.75h-3.75m3.75 0-2.25 2.25m2.25-2.25 2.25 2.25M4.5 6.75 6.75 4.5"
+						/>
+					</svg>
+					Copy
+				{/if}
+			</button>
+		</div>
+	</div>
+</div>