v0.13.2

Multi recipient send (#5)

* Support multi-recipient sends

The daemon's /api/wallet/send now requires a recipients[] array and no
longer accepts the old flat { address, amount, memo_text } body, so
single-recipient sends through the GUI were failing.

Changes:
- main.js: wrap the primary recipient in { recipients: [...] } and read
  memo_hex from result.recipients[0] (moved from the top level of the
  response). Refactor showResolved / hideResolved / debouncedResolve /
  showAddressSuggestions / hideAddressSuggestions and
  applyPaymentRequestToSend to be row-scoped. Add addRecipientRow /
  removeRecipientRow / renumberRecipientRows / updateSendTotal /
  resetSendForm / wireRecipientRow. Refactor handleSend to validate
  each row, resolve every $/@handle independently, arm/confirm with a
  per-recipient or aggregate message, and post all rows in one
  recipients[] payload. After success, auto-add every resolved handle
  to the address book and reset the form.
- index.html: wrap the existing inputs in .recipient-row (data-role
  attrs plus legacy IDs for deep-link / save-contact / ab-use
  compatibility) inside #send-recipients, add "+ Add Recipient"
  button and a running Total row.
- styles.css: new rules for .recipient-row(.extra-recipient),
  .recipient-row-header, .recipient-row-label, .recipient-remove-btn
  (orange outline), .add-recipient-btn (full-width secondary) and
  .send-total.

* Bump to core 0.13.2

Pulled the v0.13.2 daemon binaries from blocknetprivacy/core via
scripts/update-core-binaries.sh and ran sync:version to match
VERSION, package.json, src-tauri/Cargo.toml and
src-tauri/tauri.conf.json. sync:version:check passes locally on
all three platform binaries.