feat: add reusable pattern components (PR2)

Create src/components/patterns/ with 6 pure-presentation components
that abstract repeated layout patterns from settings/bridge pages:

- SettingsCard: rounded card with optional title/description
- FieldRow: label+description left, control right, optional separator
- SectionPage: max-width page container with consistent spacing
- StatusBanner: success/warning/error/info inline status messages
- EmptyState: centered empty state with icon, title, description, action
- IconAction: ghost icon button with optional tooltip wrapper

All components are zero-side-effect, only import from React and @/lib/utils
(plus ui/button and ui/tooltip for IconAction).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/patterns/EmptyState.tsx

@@ -0,0 +1,23 @@
+import { type ReactElement, type ReactNode } from "react";
+import { cn } from "@/lib/utils";
+
+interface EmptyStateProps {
+  icon?: ReactElement;
+  title: string;
+  description?: string;
+  action?: ReactNode;
+  className?: string;
+}
+
+export function EmptyState({ icon, title, description, action, className }: EmptyStateProps) {
+  return (
+    <div className={cn("flex flex-col items-center justify-center py-12 text-center", className)}>
+      {icon && <div className="mb-4 text-muted-foreground">{icon}</div>}
+      <h3 className="text-sm font-medium">{title}</h3>
+      {description && (
+        <p className="mt-1 text-xs text-muted-foreground max-w-sm">{description}</p>
+      )}
+      {action && <div className="mt-4">{action}</div>}
+    </div>
+  );
+}

src/components/patterns/FieldRow.tsx

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+import { type ReactNode } from "react";
+import { cn } from "@/lib/utils";
+
+interface FieldRowProps {
+  label: string;
+  description?: string;
+  children: ReactNode;
+  separator?: boolean;
+  className?: string;
+}
+
+export function FieldRow({ label, description, children, separator, className }: FieldRowProps) {
+  return (
+    <div className={cn(
+      "flex items-center justify-between gap-4",
+      separator && "border-t border-border/30 pt-4",
+      className
+    )}>
+      <div className="space-y-0.5 flex-1 min-w-0">
+        <div className="text-sm font-medium">{label}</div>
+        {description && (
+          <div className="text-xs text-muted-foreground">{description}</div>
+        )}
+      </div>
+      <div className="flex-shrink-0">{children}</div>
+    </div>
+  );
+}

src/components/patterns/IconAction.tsx

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+import { type ReactElement, forwardRef, type ComponentPropsWithoutRef } from "react";
+import { cn } from "@/lib/utils";
+import { Button } from "@/components/ui/button";
+import { Tooltip, TooltipContent, TooltipTrigger } from "@/components/ui/tooltip";
+
+interface IconActionProps extends Omit<ComponentPropsWithoutRef<typeof Button>, "variant" | "size" | "children"> {
+  icon: ReactElement;
+  tooltip?: string;
+  size?: "sm" | "md";
+}
+
+export const IconAction = forwardRef<HTMLButtonElement, IconActionProps>(
+  function IconAction({ icon, tooltip, size = "md", className, ...props }, ref) {
+    const button = (
+      <Button
+        ref={ref}
+        variant="ghost"
+        size="icon"
+        className={cn(
+          size === "sm" ? "h-7 w-7" : "h-8 w-8",
+          className
+        )}
+        {...props}
+      >
+        {icon}
+      </Button>
+    );
+
+    if (tooltip) {
+      return (
+        <Tooltip>
+          <TooltipTrigger asChild>{button}</TooltipTrigger>
+          <TooltipContent>{tooltip}</TooltipContent>
+        </Tooltip>
+      );
+    }
+
+    return button;
+  }
+);

src/components/patterns/SectionPage.tsx

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+import { type ReactNode } from "react";
+import { cn } from "@/lib/utils";
+
+const maxWidthMap = {
+  sm: "max-w-xl",
+  md: "max-w-2xl",
+  lg: "max-w-3xl",
+} as const;
+
+interface SectionPageProps {
+  children: ReactNode;
+  maxWidth?: "sm" | "md" | "lg";
+  className?: string;
+}
+
+export function SectionPage({ children, maxWidth = "lg", className }: SectionPageProps) {
+  return (
+    <div className={cn("mx-auto w-full space-y-6", maxWidthMap[maxWidth], className)}>
+      {children}
+    </div>
+  );
+}

src/components/patterns/SettingsCard.tsx

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+import { type ReactNode } from "react";
+import { cn } from "@/lib/utils";
+
+interface SettingsCardProps {
+  title?: string;
+  description?: string;
+  children: ReactNode;
+  className?: string;
+}
+
+export function SettingsCard({ title, description, children, className }: SettingsCardProps) {
+  return (
+    <div className={cn("rounded-lg border border-border/50 p-4 space-y-4 transition-shadow hover:shadow-sm", className)}>
+      {(title || description) && (
+        <div className="space-y-1">
+          {title && <h3 className="text-sm font-medium">{title}</h3>}
+          {description && <p className="text-xs text-muted-foreground">{description}</p>}
+        </div>
+      )}
+      {children}
+    </div>
+  );
+}

src/components/patterns/StatusBanner.tsx

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+import { type ReactElement, type ReactNode } from "react";
+import { cn } from "@/lib/utils";
+
+const variantStyles = {
+  success: "bg-green-500/10 text-green-600 dark:text-green-400",
+  warning: "bg-orange-500/10 text-orange-600 dark:text-orange-400",
+  error: "bg-red-500/10 text-red-600 dark:text-red-400",
+  info: "bg-blue-500/10 text-blue-600 dark:text-blue-400",
+} as const;
+
+interface StatusBannerProps {
+  variant: "success" | "warning" | "error" | "info";
+  icon?: ReactElement;
+  children: ReactNode;
+  className?: string;
+}
+
+export function StatusBanner({ variant, icon, children, className }: StatusBannerProps) {
+  return (
+    <div className={cn(
+      "flex items-center gap-2 rounded-md px-3 py-2 text-xs",
+      variantStyles[variant],
+      className
+    )}>
+      {icon && <div className="flex-shrink-0">{icon}</div>}
+      <div className="flex-1 min-w-0">{children}</div>
+    </div>
+  );
+}

src/components/patterns/index.ts

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+export { SettingsCard } from "./SettingsCard";
+export { FieldRow } from "./FieldRow";
+export { SectionPage } from "./SectionPage";
+export { StatusBanner } from "./StatusBanner";
+export { EmptyState } from "./EmptyState";
+export { IconAction } from "./IconAction";