feat(clink): pay CLINK noffer offers from notes, profiles & wallet

[dmnyc]

Summary

Adds CLINK Offers (noffer1…) payment support so users can pay self-custodial Lightning offers advertised in notes, on profiles, and from the wallet — matching the established "scan to pay" UX in Wisp style.

• Decoder + RPC — Noffer: bech32 + TLV decoder, pricing types (fixed / variable-range / spontaneous), isNofferString / stripNostrPrefix. NofferClient: kind-21001 NIP-44 RPC (publish request → await the encrypted invoice on the offer's relay → pay), with code-3 "expired/moved" latest-retry.
• Pay modal — NofferPaySheet + NofferButton: a shared "Pay offer" sheet that pays via the active wallet, or falls back to a scannable bare-noffer QR for an external CLINK-aware wallet. The inline card resolves the recipient's name itself so it reads consistently across feed and thread.
• Notes — ContentParser detects noffer tokens (incl. nostr: prefix); RichContentView renders the Pay-offer card.
• Profiles — parse clink_offer / noffer / offer from kind-0 (tolerant read); Pay-offer button on the profile header; a CLINK offer field in the profile editor's Advanced section.
• Profile QR sheet — the offer lives inside the Lightning tab (not a separate tab); when a profile has both a Lightning address and an offer, a single contextual button switches between them. Gated away entirely when no offer is set.
• Wallet Send sheet — detects a pasted/scanned noffer and opens the pay flow; the input placeholder now reads "Lightning address, invoice, or CLINK offer".
• Tests — round-trip decoder coverage mirroring the CLINK spec TLV layout.

Spec: https://github.com/shocknet/CLINK/blob/main/specs/clink-offers.md

Test plan

• Note "Pay offer" card → in-app payment settles
• Note "Pay offer" card → external QR scans/pays from a CLINK-aware wallet
• Wallet Send sheet → pasted/scanned noffer opens the pay flow
• Profile header Pay-offer button → opens the sheet and pays
• Profile QR sheet → offer shows in the Lightning tab with the contextual switch
• CLINK offer round-trips through kind-0 (set in profile, renders everywhere)
• Recipient name resolves consistently (feed + thread)
• Fixed-amount and variable-range pricing variants (only "pay what you want" exercised so far — to verify over time)

Android port to follow.

[dmnyc]

Changing to draft mode so this can deploy in Dark Wisp first. barrydeen/dark-wisp-android#25