feat(web): add Modal + EmptyState primitives and a11y hooks

- Modal: shared backdrop/panel with ESC-close, backdrop-click-close,
  focus trap, body scroll lock; supports center + drawer-right variants,
  matrix/violet accents, default/wide widths.
- EmptyState: icon + title + hint + optional CTA; compact variant
  for tight rails.
- useEscapeKey, useFocusTrap: reusable hooks powering Modal; will also
  be adopted by CommandPalette and ContextMenu in follow-up commits.

No retrofits yet — primitives only. tsc clean.

decnet_web/src/components/EmptyState/EmptyState.css

@@ -0,0 +1,52 @@
+/* Shared EmptyState styling. Component-scoped .empty-state rules
+   (Attackers/Bounty/LiveLogs) still win over these base rules. */
+
+.empty-state-icon {
+  opacity: 0.4;
+  color: var(--violet);
+}
+
+.empty-state-title {
+  font-size: 0.75rem;
+  letter-spacing: 2px;
+  opacity: 0.7;
+}
+
+.empty-state-hint {
+  font-size: 0.65rem;
+  opacity: 0.45;
+  letter-spacing: 1px;
+  margin-top: -4px;
+}
+
+.empty-state-cta {
+  margin-top: 6px;
+  padding: 6px 12px;
+  background: transparent;
+  border: 1px solid var(--matrix);
+  color: var(--matrix);
+  font-family: var(--font-mono);
+  font-size: 0.65rem;
+  letter-spacing: 2px;
+  cursor: pointer;
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  text-transform: uppercase;
+}
+
+.empty-state-cta:hover {
+  background: rgba(0, 255, 65, 0.1);
+  box-shadow: 0 0 8px rgba(0, 255, 65, 0.3);
+}
+
+.empty-state.empty-state-compact {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  padding: 6px 4px;
+  font-size: 0.65rem;
+  letter-spacing: 1.5px;
+  opacity: 0.5;
+  color: var(--text-dim, #888);
+}

decnet_web/src/components/EmptyState/EmptyState.tsx

@@ -0,0 +1,46 @@
+import React from 'react';
+import type { LucideIcon } from 'lucide-react';
+import './EmptyState.css';
+
+interface CTA {
+  label: string;
+  onClick: () => void;
+  icon?: LucideIcon;
+}
+
+interface Props {
+  icon?: LucideIcon;
+  title: string;
+  hint?: string;
+  cta?: CTA;
+  size?: 'default' | 'compact';
+  className?: string;
+}
+
+const EmptyState: React.FC<Props> = ({ icon: Icon, title, hint, cta, size = 'default', className = '' }) => {
+  if (size === 'compact') {
+    return (
+      <div className={`empty-state empty-state-compact ${className}`}>
+        {Icon && <Icon size={12} />}
+        <span>{title}</span>
+      </div>
+    );
+  }
+
+  const CtaIcon = cta?.icon;
+  return (
+    <div className={`empty-state ${className}`}>
+      {Icon && <Icon size={28} className="empty-state-icon" />}
+      <div className="type-label empty-state-title">{title}</div>
+      {hint && <div className="empty-state-hint">{hint}</div>}
+      {cta && (
+        <button type="button" className="empty-state-cta" onClick={cta.onClick}>
+          {CtaIcon && <CtaIcon size={12} />}
+          <span>{cta.label}</span>
+        </button>
+      )}
+    </div>
+  );
+};
+
+export default EmptyState;

decnet_web/src/components/Modal/Modal.css

@@ -0,0 +1,24 @@
+/* Drawer-right variant: reuses .modal-backdrop + .modal base from DeckyFleet.css
+   and shifts the panel to the right edge as a full-height side panel. */
+
+.modal-backdrop.drawer {
+  justify-content: flex-end;
+  align-items: stretch;
+}
+
+.modal.modal-drawer-right {
+  width: 520px;
+  max-width: 96vw;
+  max-height: 100vh;
+  height: 100vh;
+  border-left: 1px solid var(--matrix);
+  border-top: none;
+  border-right: none;
+  border-bottom: none;
+  box-shadow: -8px 0 30px rgba(0, 0, 0, 0.6);
+}
+
+.modal.modal-drawer-right.violet {
+  border-left-color: var(--violet);
+  box-shadow: -8px 0 30px rgba(238, 130, 238, 0.25);
+}

decnet_web/src/components/Modal/Modal.tsx

@@ -0,0 +1,85 @@
+import React, { useEffect, useRef } from 'react';
+import { X, type LucideIcon } from 'lucide-react';
+import { useEscapeKey } from '../../hooks/useEscapeKey';
+import { useFocusTrap } from '../../hooks/useFocusTrap';
+import './Modal.css';
+
+interface Props {
+  open: boolean;
+  onClose: () => void;
+  title?: string;
+  icon?: LucideIcon;
+  footer?: React.ReactNode;
+  accent?: 'matrix' | 'violet';
+  width?: 'default' | 'wide';
+  variant?: 'center' | 'drawer-right';
+  children: React.ReactNode;
+  className?: string;
+}
+
+const Modal: React.FC<Props> = ({
+  open,
+  onClose,
+  title,
+  icon: Icon,
+  footer,
+  accent = 'matrix',
+  width = 'default',
+  variant = 'center',
+  children,
+  className = '',
+}) => {
+  const panelRef = useRef<HTMLDivElement | null>(null);
+
+  useEscapeKey(onClose, open);
+  useFocusTrap(panelRef, open);
+
+  useEffect(() => {
+    if (!open) return;
+    const prev = document.body.style.overflow;
+    document.body.style.overflow = 'hidden';
+    return () => {
+      document.body.style.overflow = prev;
+    };
+  }, [open]);
+
+  if (!open) return null;
+
+  const panelClasses = [
+    'modal',
+    accent === 'violet' ? 'violet' : '',
+    width === 'wide' ? 'wide' : '',
+    variant === 'drawer-right' ? 'modal-drawer-right' : '',
+    className,
+  ].filter(Boolean).join(' ');
+
+  const backdropClass = variant === 'drawer-right' ? 'modal-backdrop drawer' : 'modal-backdrop';
+
+  return (
+    <div className={backdropClass} onClick={onClose}>
+      <div
+        ref={panelRef}
+        className={panelClasses}
+        onClick={(e) => e.stopPropagation()}
+        role="dialog"
+        aria-modal="true"
+      >
+        {title && (
+          <div className="modal-head">
+            <h3>
+              {Icon && <Icon size={14} />}
+              {title}
+            </h3>
+            <button className="close-btn" onClick={onClose} aria-label="Close">
+              <X size={16} />
+            </button>
+          </div>
+        )}
+        {children}
+        {footer && <div className="modal-foot">{footer}</div>}
+      </div>
+    </div>
+  );
+};
+
+export default Modal;

decnet_web/src/hooks/useEscapeKey.ts

@@ -0,0 +1,15 @@
+import { useEffect } from 'react';
+
+export function useEscapeKey(onEscape: () => void, active: boolean = true): void {
+  useEffect(() => {
+    if (!active) return;
+    const handler = (e: KeyboardEvent) => {
+      if (e.key === 'Escape') {
+        e.stopPropagation();
+        onEscape();
+      }
+    };
+    window.addEventListener('keydown', handler);
+    return () => window.removeEventListener('keydown', handler);
+  }, [onEscape, active]);
+}

decnet_web/src/hooks/useFocusTrap.ts

@@ -0,0 +1,49 @@
+import { useEffect, type RefObject } from 'react';
+
+const FOCUSABLE =
+  'input:not([disabled]), button:not([disabled]), textarea:not([disabled]), select:not([disabled]), a[href], [tabindex]:not([tabindex="-1"])';
+
+export function useFocusTrap(
+  ref: RefObject<HTMLElement | null>,
+  active: boolean,
+): void {
+  useEffect(() => {
+    if (!active || !ref.current) return;
+    const root = ref.current;
+    const previouslyFocused = document.activeElement as HTMLElement | null;
+
+    const focusables = () =>
+      Array.from(root.querySelectorAll<HTMLElement>(FOCUSABLE)).filter(
+        (el) => !el.hasAttribute('aria-hidden') && el.offsetParent !== null,
+      );
+
+    const autoFocus =
+      root.querySelector<HTMLElement>('[data-autofocus]') ?? focusables()[0];
+    autoFocus?.focus();
+
+    const handler = (e: KeyboardEvent) => {
+      if (e.key !== 'Tab') return;
+      const items = focusables();
+      if (items.length === 0) {
+        e.preventDefault();
+        return;
+      }
+      const first = items[0];
+      const last = items[items.length - 1];
+      const current = document.activeElement as HTMLElement | null;
+      if (e.shiftKey && current === first) {
+        e.preventDefault();
+        last.focus();
+      } else if (!e.shiftKey && current === last) {
+        e.preventDefault();
+        first.focus();
+      }
+    };
+
+    root.addEventListener('keydown', handler);
+    return () => {
+      root.removeEventListener('keydown', handler);
+      previouslyFocused?.focus?.();
+    };
+  }, [ref, active]);
+}