Add export method dialog, extract shared Dialog primitive

Add export dialog with download/clipboard options and optional
undo/redo history inclusion (default off). Extract shared Dialog
component to ui/dialog.tsx, consolidating open/close lifecycle,
backdrop click, and escape key handling from all 6 dialog components.
Update spec to reflect export method dialog and optional history.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/web/src/components/export-method-dialog.tsx

@@ -0,0 +1,94 @@
+import { Check, ClipboardCopy, Download, X } from "lucide-react";
+import { useCallback, useState } from "react";
+import { Button } from "./ui/button.js";
+import { Dialog } from "./ui/dialog.js";
+
+interface ExportMethodDialogProps {
+	open: boolean;
+	onDownload: (includeHistory: boolean) => void;
+	onCopyToClipboard: (includeHistory: boolean) => void;
+	onClose: () => void;
+}
+
+export function ExportMethodDialog({
+	open,
+	onDownload,
+	onCopyToClipboard,
+	onClose,
+}: Readonly<ExportMethodDialogProps>) {
+	const [includeHistory, setIncludeHistory] = useState(false);
+	const [copied, setCopied] = useState(false);
+
+	const handleClose = useCallback(() => {
+		setIncludeHistory(false);
+		setCopied(false);
+		onClose();
+	}, [onClose]);
+
+	return (
+		<Dialog open={open} onClose={handleClose} className="w-80">
+			<div className="mb-4 flex items-center justify-between">
+				<h2 className="font-semibold text-lg">Export Encounter</h2>
+				<Button
+					type="button"
+					variant="ghost"
+					size="icon-sm"
+					onClick={handleClose}
+					className="text-muted-foreground"
+				>
+					<X className="h-4 w-4" />
+				</Button>
+			</div>
+			<label className="mb-4 flex items-center gap-2 text-sm">
+				<input
+					type="checkbox"
+					checked={includeHistory}
+					onChange={(e) => setIncludeHistory(e.target.checked)}
+					className="accent-accent"
+				/>
+				<span className="text-foreground">Include undo/redo history</span>
+			</label>
+			<div className="flex flex-col gap-2">
+				<button
+					type="button"
+					className="flex items-center gap-3 rounded-lg border border-border px-4 py-3 text-left text-foreground text-sm hover:bg-hover-neutral-bg"
+					onClick={() => {
+						onDownload(includeHistory);
+						handleClose();
+					}}
+				>
+					<Download className="h-5 w-5 text-muted-foreground" />
+					<div>
+						<div className="font-medium">Download file</div>
+						<div className="text-muted-foreground text-xs">
+							Save as a JSON file
+						</div>
+					</div>
+				</button>
+				<button
+					type="button"
+					className="flex items-center gap-3 rounded-lg border border-border px-4 py-3 text-left text-foreground text-sm hover:bg-hover-neutral-bg"
+					onClick={() => {
+						onCopyToClipboard(includeHistory);
+						setCopied(true);
+						setTimeout(() => setCopied(false), 2000);
+					}}
+				>
+					{copied ? (
+						<Check className="h-5 w-5 text-green-400" />
+					) : (
+						<ClipboardCopy className="h-5 w-5 text-muted-foreground" />
+					)}
+					<div>
+						<div className="font-medium">
+							{copied ? "Copied!" : "Copy to clipboard"}
+						</div>
+						<div className="text-muted-foreground text-xs">
+							Copy JSON to your clipboard
+						</div>
+					</div>
+				</button>
+			</div>
+		</Dialog>
+	);
+}