feat: local country flags replacing team crests

48 country flags downloaded from flagcdn.com (320px PNG, ~55KB total)
stored in frontend/public/flags/{iso-code}.png.

New utility getFlagUrl() maps team names to local flag files.
Applied to MatchCard, DashboardPage, and TipModal.
Falls back to original crest URL if no mapping exists (e.g. TBD).

No external API calls at runtime — all flags served statically.

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

frontend/src/components/TipModal.tsx

@@ -1,5 +1,6 @@
 import { useState } from 'react';
 import { Match, api } from '../api/client';
+import { getFlagUrl } from '../utils/flagUrl';
 import styles from './TipModal.module.css';
 
 interface Props {
@@ -63,8 +64,8 @@ export default function TipModal({ match, onClose, onSaved }: Props) {
         <div className={styles.teamsRow}>
           <div className={styles.teamBlock}>
             <div className={styles.flagLarge}>
-              {match.homeTeam.crest
-                ? <img src={match.homeTeam.crest} alt={match.homeTeam.name} className={styles.flagImg} />
+              {match.homeTeam.name
+                ? <img src={getFlagUrl(match.homeTeam.name, match.homeTeam.crest)} alt={match.homeTeam.name} className={styles.flagImg} />
                 : <span className={styles.flagEmoji}>🏳️</span>
               }
             </div>
@@ -75,8 +76,8 @@ export default function TipModal({ match, onClose, onSaved }: Props) {
 
           <div className={styles.teamBlock}>
             <div className={styles.flagLarge}>
-              {match.awayTeam.crest
-                ? <img src={match.awayTeam.crest} alt={match.awayTeam.name} className={styles.flagImg} />
+              {match.awayTeam.name
+                ? <img src={getFlagUrl(match.awayTeam.name, match.awayTeam.crest)} alt={match.awayTeam.name} className={styles.flagImg} />
                 : <span className={styles.flagEmoji}>🏳️</span>
               }
             </div>