Borrower: Create Offer modal

[ardier16]

Describe the feature

Description:
Implement single-form modal for borrowers to create lending offers, followed by processing and success states.

Acceptance Criteria:

• Single Create Borrow Offer modal implemented (one form):
  • Collateral amount (auto-filled from UTXO)
  • Loan amount input (USDT)
  • Fee input (USDT)
  • Duration/Term selector (days/blocks)
  • Derived values shown in real-time: APR (%) and LTV (%)
  • Inline validation states and disabled submit when invalid
  • Single CTA: "Create Borrow Offer"
• Processing modal/state after submit:
  • Show staged progress states (validating offer, checking limits, creating tx, broadcasting)
  • Pending state with spinner/progress
  • Success state with txid and link to Esplora
  • Error state with retry and clear reason
• localStorage persistence:
  • Save in-progress form values
  • Restore draft on refresh before submission
• Transaction builders called:
  • buildPrepareUtilityNftsTx() — prepare 4 utility UTXOs
  • buildIssueUtilityNftsTx() — issue NFTs
  • buildPreLockCreationTx() — create pre-lock
• All tx signing via Jade (Jade wallet integration #24)
• Manual test: Complete single-form offer creation flow on testnet, verify on Esplora

Notes:

• Modal closes on success; returns to Dashboard
• Keep UX aligned with Figma: one form modal + processing state modal
• localStorage key: borrower_offer_draft