feat: add transaction hash search to blockchain explorer and cleanup settlement storage

Blockchain Explorer:
- Add transaction hash search support (64-char hex pattern validation)
- Fetch and display transaction details in modal (hash, type, from/to, amount, fee, block)
- Fix regex escape sequence in block height validation
- Update search placeholder text to mention both search types
- Add blank lines between function definitions for PEP 8 compliance

Settlement Storage:
- Add timedelta import for future

website/docs/wallet-daemon.html

@@ -178,7 +178,7 @@ print(f"Address: {wallet.address}")
 tx = client.send_transaction(
     to="0x123...",
     amount=1000,
-    password="password"
+    password="${PASSWORD}"
 )
 print(f"Transaction hash: {tx.hash}")</code></pre>