fix: say a contract creation has no recipient instead of a blank line (closes #250)

A transaction with no `to` showed a blank recipient line on the wait,
success and error screens and the transaction detail view: an empty
address, with a colour dot whose colour was `undefined`. The approval
screen showed "(contract creation)".

All five now say "This transaction creates a new contract. It has no
recipient." A transaction with a real `to` is unchanged. The new test
drives each screen both ways.

Model: opus-5-5

README.md

@@ -1437,7 +1437,9 @@ view would leave a wallet one click from deletion.
 - **Elements**:
     - "Transaction Broadcast" heading (no back button — tx is irreversible)
     - Amount + symbol
-    - To: color dot + full address + etherscan link
+    - To: color dot + full address + etherscan link; for a contract creation,
+      which has no recipient, "This transaction creates a new contract. It has
+      no recipient." instead
     - Transaction hash: full hash (tap to copy) + etherscan link
     - Count-up timer: "Waiting for confirmation... Ns"
 - **Behavior**: Polls `getTransactionReceipt` every 10 seconds. The wait is
@@ -1466,7 +1468,8 @@ view would leave a wallet one click from deletion.
     - Decoded action well (shown when the transaction carried recognized
       calldata; the top-level Amount and To are hidden in that case)
     - Amount + symbol
-    - To: color dot + full address + etherscan link
+    - To: color dot + full address + etherscan link, or for a contract creation
+      the same sentence as on WaitTx
     - Block number
     - Transaction hash: full hash (tap to copy) + etherscan link
     - "Done" button
@@ -1481,7 +1484,8 @@ view would leave a wallet one click from deletion.
 - **Elements**:
     - "Transaction Failed" heading
     - Amount + symbol
-    - To: color dot + full address + etherscan link
+    - To: color dot + full address + etherscan link, or for a contract creation
+      the same sentence as on WaitTx
     - Error message (dashed border box)
     - Transaction hash section (hidden if broadcast failed before getting hash):
       full hash (tap to copy) + etherscan link
@@ -1519,7 +1523,7 @@ view would leave a wallet one click from deletion.
     - From: blockie + color dot + full address (tap to copy) + etherscan link;
       ENS name if available
     - To: blockie + color dot + full address (tap to copy) + etherscan link; ENS
-      name if available
+      name if available. For a contract creation, the same sentence as on WaitTx
     - Time: ISO datetime + relative age in parentheses
     - Block: block number (tap to copy) + etherscan block link
     - Amount: value + symbol (bold)
@@ -1830,8 +1834,8 @@ view would leave a wallet one click from deletion.
     - Decoded action (if calldata is recognized): action name, token details,
       amounts, steps, deadline (see Transaction Decoding)
     - From: color dot + full address + etherscan link
-    - Contract: color dot + full address + etherscan link (or "contract
-      creation"), token symbol label if known
+    - Contract: color dot + full address + etherscan link, token symbol label if
+      known; for a contract creation, the same sentence as on WaitTx
     - Value: amount in ETH (4 decimal places, USD in parentheses)
     - Network fee (max): gas limit × fee per gas in ETH (4 decimal places, USD
       in parentheses), with the gas limit and the fee per gas in gwei below it