feat(rfq): persist wallet destination catalog - #33

Summary

• add an identity-bound redb wallet catalog that persists random destination locators before exposure
• add bounded, authenticated wallet-only export/restore with exact encrypted-keystore preservation and explicit stale-backup semantics
• harden Unix storage publication with owner and permission checks, lock probing, no-clobber staging, inode verification, ambiguous-commit poisoning, and published-but-unconfirmed recovery guidance
• move production destination issuance behind the persistent wallet and add authenticated owned-output recovery
• update the RFQ ADRs, roadmap, and current-state documentation

Scope

This remains transport-free. The Elements-backed inventory/chain scanner, unattended passphrase delivery, daemon integration, coordinated provider-state recovery, and remote RFQ protocol remain follow-up work.

Validation

• nix develop .#default --command just ci
• 370 tests passed, 6 skipped
• all five live Liquid regtest gates passed
• 37 focused deadcat-rfq-wallet tests passed
• strict workspace Clippy, formatting, documentation, and WASM checks passed

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