refactor(ts): convert app-wide common components to TSX (B8)

PageLoader, PageTransition, StatusBadge (top-level), MarkdownText (typed
renderInlineMarkdown, isValidElement for keys), and ErrorBoundary (typed class
component: ErrorBoundaryProps/State, getDerivedStateFromError, ErrorInfo;
generic withErrorBoundary<P> HOC). typecheck 0, build green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/components/ErrorBoundary.tsx

@@ -1,27 +1,36 @@
-import React from 'react';
+import React, { type ReactNode } from 'react';
 import { AlertTriangle, RefreshCw } from 'lucide-react';
 import { Button } from '@/components/ui/button';
-import { cn } from '@/lib/utils';
 
 // ────────────────────────────────────────────────────────────────────────────
 // ErrorBoundary Component
 // ────────────────────────────────────────────────────────────────────────────
-class ErrorBoundary extends React.Component {
-  constructor(props) {
+interface ErrorBoundaryProps {
+  children?: ReactNode;
+}
+
+interface ErrorBoundaryState {
+  hasError: boolean;
+  error: Error | null;
+  componentStack: string | null;
+}
+
+class ErrorBoundary extends React.Component<ErrorBoundaryProps, ErrorBoundaryState> {
+  constructor(props: ErrorBoundaryProps) {
     super(props);
     this.state = { hasError: false, error: null, componentStack: null };
   }
 
-  static getDerivedStateFromError(error) {
+  static getDerivedStateFromError(error: Error): Partial<ErrorBoundaryState> {
     return { hasError: true, error };
   }
 
-  componentDidCatch(error, info) {
+  componentDidCatch(error: Error, info: React.ErrorInfo) {
     console.error('ErrorBoundary caught an error:', {
       error,
       componentStack: info?.componentStack,
     });
-    this.setState({ error, componentStack: info?.componentStack });
+    this.setState({ error, componentStack: info?.componentStack ?? null });
   }
 
   handleReset = () => {
@@ -102,8 +111,11 @@ class ErrorBoundary extends React.Component {
 // ────────────────────────────────────────────────────────────────────────────
 // withErrorBoundary HOC
 // ────────────────────────────────────────────────────────────────────────────
-export function withErrorBoundary(Component, displayName = Component.name || 'Component') {
-  function WrappedComponent(props) {
+export function withErrorBoundary<P extends object>(
+  Component: React.ComponentType<P>,
+  displayName: string = Component.displayName || Component.name || 'Component',
+) {
+  function WrappedComponent(props: P) {
     return (
       <ErrorBoundary>
         <Component {...props} />

client/components/MarkdownText.tsx

@@ -1,8 +1,8 @@
-import { Fragment } from 'react';
+import { Fragment, isValidElement, type ReactNode } from 'react';
 
 const TOKEN_RE = /(\*\*[^*\n][\s\S]*?[^*\n]\*\*|`[^`\n]+`|\[[^\]\n]+\]\(https?:\/\/[^)\s]+\))/g;
 
-function renderToken(token, key) {
+function renderToken(token: string, key: string): ReactNode {
   if (token.startsWith('**') && token.endsWith('**')) {
     return (
       <strong key={key} className="font-semibold text-foreground">
@@ -37,18 +37,19 @@ function renderToken(token, key) {
   return token;
 }
 
-export function renderInlineMarkdown(text) {
+export function renderInlineMarkdown(text: string | null | undefined): ReactNode {
   if (!text) return null;
 
-  const parts = [];
+  const parts: ReactNode[] = [];
   let lastIndex = 0;
 
   for (const match of text.matchAll(TOKEN_RE)) {
-    if (match.index > lastIndex) {
-      parts.push(text.slice(lastIndex, match.index));
+    const mi = match.index ?? 0;
+    if (mi > lastIndex) {
+      parts.push(text.slice(lastIndex, mi));
     }
-    parts.push(renderToken(match[0], `md-${match.index}`));
-    lastIndex = match.index + match[0].length;
+    parts.push(renderToken(match[0], `md-${mi}`));
+    lastIndex = mi + match[0].length;
   }
 
   if (lastIndex < text.length) {
@@ -56,12 +57,12 @@ export function renderInlineMarkdown(text) {
   }
 
   return parts.map((part, index) => (
-    <Fragment key={typeof part === 'string' ? `text-${index}` : part.key || index}>
+    <Fragment key={isValidElement(part) ? (part.key ?? index) : `text-${index}`}>
       {part}
     </Fragment>
   ));
 }
 
-export function MarkdownText({ text }) {
+export function MarkdownText({ text }: { text?: string | null }): ReactNode {
   return renderInlineMarkdown(text);
 }

client/components/PageTransition.tsx

@@ -1,6 +1,7 @@
 import { AnimatePresence, motion, useReducedMotion } from 'framer-motion';
+import type { ReactNode } from 'react';
 
-export default function PageTransition({ children, routeKey }) {
+export default function PageTransition({ children, routeKey }: { children: ReactNode; routeKey?: string }) {
   const reduceMotion = useReducedMotion();
 
   if (reduceMotion) return children;

client/components/StatusBadge.tsx

@@ -12,8 +12,8 @@ const STATUS_META = {
   skipped:   { label: 'Skipped',   cls: 'bg-muted text-muted-foreground border border-border' },
 };
 
-export const StatusBadge = React.memo(function StatusBadge({ status }) {
-  const meta = useMemo(() => STATUS_META[status] || STATUS_META.upcoming, [status]);
+export const StatusBadge = React.memo(function StatusBadge({ status }: { status: string }) {
+  const meta = useMemo(() => STATUS_META[status as keyof typeof STATUS_META] || STATUS_META.upcoming, [status]);
   const isUrgent = status === 'late' || status === 'missed';
   return (
     <span className={cn(