fix(ecash): repair two mangled warning messages

Both import refusals reached the operator with runs of ~18 spaces mid
sentence — "Importing a different one                  means coins
minted…". The string literals had been written as single long lines with
the line-continuation whitespace baked in rather than escaped, so Rust
preserved it verbatim.

Only visible once the sanitizer stopped swallowing these messages, which
is its own small lesson: the text had been wrong since it was written and
nothing could show it.

Cosmetic, but not trivially so — this is the warning that stops someone
replacing the phrase their balance was minted under, and text that looks
broken is text people stop reading.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

core/archipelago/src/wallet/nut13.rs

@@ -282,7 +282,9 @@ pub async fn establish_independent(data_dir: &Path) -> Result<EcashSeed> {
 pub async fn import_mnemonic(data_dir: &Path, words: &str, confirm: bool) -> Result<EcashSeed> {
     let mnemonic: bip39::Mnemonic = words.split_whitespace().collect::<Vec<_>>().join(" ").parse()
         .map_err(|e| anyhow::anyhow!(
-            "That is not a valid BIP-39 recovery phrase: {e}. Check for typos —              every word must come from the BIP-39 word list, and the phrase as a              whole carries a checksum."
+            "That is not a valid BIP-39 recovery phrase: {e}. Check for typos — \
+             every word must come from the BIP-39 word list, and the phrase as \
+             a whole carries a checksum."
         ))?;
 
     if let Some(existing) = load_seed(data_dir).await? {
@@ -293,7 +295,11 @@ pub async fn import_mnemonic(data_dir: &Path, words: &str, confirm: bool) -> Res
         }
         if !confirm {
             anyhow::bail!(
-                "This wallet already has a backup phrase. Importing a different one                  means coins minted under the current phrase will no longer be                  restorable from words — they stay spendable, but a restore will not                  find them. Reveal and write down the current phrase first, then                  confirm to replace it."
+                "This wallet already has a backup phrase. Importing a different one \
+                 means coins minted under the current phrase will no longer be \
+                 restorable from words — they stay spendable, but a restore will \
+                 not find them. Reveal and write down the current phrase first, \
+                 then confirm to replace it."
             );
         }
         archive_seed(data_dir).await?;