refactor: remove NFT avatar functionality

Removes avatar-settings component, avatar-visibility store, and all
avatar rendering from posts. Strips avatar from account JSON, renames
NFT gateway label to media IPFS gateway, removes Polygon RPC and
hide-avatars toggle. Deletes 6 avatar-related translation keys.

src/components/settings-modal/crypto-wallets-setting/crypto-wallets-setting.tsx

@@ -102,7 +102,7 @@ const CryptoWalletsForm = ({ account }: { account: Account | undefined }) => {
     walletsArray.length > 0 ? (
       <div key={selectedWallet} className={styles.walletBox}>
         <div className={`${styles.walletField} ${styles.step1}`}>
-          <span className={styles.walletFieldTitle}>{capitalize(t('chain_ticker'))}: </span>
+          <span className={styles.walletFieldTitle}>Chain ticker: </span>
           <input
             type='text'
             onChange={(e) => setWalletsArrayProperty(selectedWallet, 'chainTicker', e.target.value)}