feat: dashboard UI/UX overhaul from full review

Shared foundation:
- New Modal component on native <dialog>.showModal() (focus trap, inert
  background, Escape, focus restore, scroll lock); all eight dialogs and
  both globalThis.confirm calls migrated to it
- Design tokens for success/warning/danger surfaces; pill danger variant;
  .sr-only utility; toast layering above dialog backdrops; not-allowed
  cursor for validity-disabled buttons

Conversations/attention: auto-scroll with jump-to-latest, per-conversation
draft persistence, suggestion undo, 30s auto-refresh with refresh controls,
unread emphasis and counts, blur-consistent share dialog, empty-accounts
guidance, collapsed user lookup, relative timestamps, danger pills for
critical items

Media/library/outreach: click-blurred-to-reveal, lightbox with arrow
navigation and captions, dirty-form preservation across refetches, upload
validation with thumbnail preview, save feedback, result counts with
load-more and clear-filters, ticking countdowns from a single clock

Overview/performance/operations/settings: mutation errors inside the
confirm dialog, live sending-window countdown, offline-aware loading
states, per-panel loading/error with retry, 7/30/90-day range toggle,
console scroll yielding with shown/retained counts, risky-save matching
by subreddit name instead of index, useBlocker unsaved-changes guard,
single-pass validation with focus-to-first-error, access panel JSON
validation and input reset

Tests: 806 -> 844 passing; both typechecks clean.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/dashboard/src/components/modal.tsx

@@ -0,0 +1,79 @@
+import { useEffect, useRef, useState, type PropsWithChildren, type ReactNode } from 'react';
+
+interface ModalProps {
+  /** Class applied to the <dialog> element itself (it is the visible card). */
+  className?: string;
+  /** Blocks Escape/backdrop dismissal while a mutation is in flight. */
+  isDismissLocked?: boolean;
+  /** Close when the backdrop (the ::backdrop area of the dialog) is pressed. */
+  closeOnBackdrop?: boolean;
+  label?: string;
+  labelledBy?: string;
+  onClose(): void;
+}
+
+/**
+ * Shared modal built on native <dialog>.showModal(): the browser provides
+ * focus trapping, inert background, and Escape handling. Render conditionally;
+ * mounting opens the dialog and unmounting restores focus to the opener.
+ */
+export function Modal({
+  children,
+  className,
+  closeOnBackdrop = false,
+  isDismissLocked = false,
+  label,
+  labelledBy,
+  onClose,
+}: PropsWithChildren<ModalProps>): ReactNode {
+  const dialogRef = useRef<HTMLDialogElement>(null);
+  const onCloseRef = useRef(onClose);
+  onCloseRef.current = onClose;
+  const dismissLockedRef = useRef(isDismissLocked);
+  dismissLockedRef.current = isDismissLocked;
+
+  // Captured at first render, before autoFocus moves focus into the dialog.
+  const [previouslyFocused] = useState(() => document.activeElement);
+
+  useEffect(() => {
+    const dialog = dialogRef.current;
+    if (!dialog) return;
+    if (!dialog.open) {
+      if (typeof dialog.showModal === 'function') dialog.showModal();
+      else dialog.setAttribute('open', '');
+    }
+    return () => {
+      if (previouslyFocused instanceof HTMLElement && previouslyFocused.isConnected) {
+        previouslyFocused.focus();
+      }
+    };
+  }, [previouslyFocused]);
+
+  function requestClose(): void {
+    if (!dismissLockedRef.current) onCloseRef.current();
+  }
+
+  return (
+    <dialog
+      aria-label={label}
+      aria-labelledby={labelledBy}
+      className={className ? `modal ${className}` : 'modal'}
+      onCancel={(event) => {
+        event.preventDefault();
+        requestClose();
+      }}
+      onKeyDown={(event) => {
+        if (event.key === 'Escape') {
+          event.preventDefault();
+          requestClose();
+        }
+      }}
+      onMouseDown={(event) => {
+        if (closeOnBackdrop && event.target === event.currentTarget) requestClose();
+      }}
+      ref={dialogRef}
+    >
+      {children}
+    </dialog>
+  );
+}