feat(bitcoin): full Bitcoin ecosystem cards and composables (M12.2-M12.8)

M12.2: Fedimint ecash card with Fedi deep-link
M12.3: BOLT12 offer card with QR and wallet deep-link
M12.4: Nostr Wallet Connect (NWC) composable with NIP-47 scaffolding
M12.5: LNURL-auth login composable with challenge generation
M12.6: Live sat/fiat price from mempool.space/api/v1/prices (60s refresh)
M12.7: Mempool.space tx viewer with confirmations, fee rate, block height
M12.8: BOLT11 invoice decoder card with amount, expiry countdown, pay link

All Bitcoin patterns auto-detected in chat messages via useBitcoinDetector.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/app/src/composables/useBitcoinPrice.ts

@@ -0,0 +1,70 @@
+import { ref, onMounted, onBeforeUnmount } from 'vue'
+
+const price = ref<number | null>(null)
+const currency = ref('USD')
+const lastUpdated = ref<number | null>(null)
+const isLoading = ref(false)
+
+let refreshTimer: ReturnType<typeof setInterval> | null = null
+let initialized = false
+
+async function fetchPrice() {
+  isLoading.value = true
+  try {
+    const res = await fetch('https://mempool.space/api/v1/prices')
+    if (!res.ok) throw new Error('Failed to fetch price')
+    const data = await res.json()
+    price.value = data.USD ?? null
+    lastUpdated.value = Date.now()
+  } catch {
+    // Keep existing price on error
+  } finally {
+    isLoading.value = false
+  }
+}
+
+export function useBitcoinPrice() {
+  function formatPrice(usd: number | null): string {
+    if (usd === null) return '...'
+    return '$' + usd.toLocaleString('en-US', { minimumFractionDigits: 0, maximumFractionDigits: 0 })
+  }
+
+  function satsToUsd(sats: number): string {
+    if (!price.value) return '...'
+    const usd = (sats / 100000000) * price.value
+    if (usd < 0.01) return '<$0.01'
+    return '$' + usd.toFixed(2)
+  }
+
+  function usdToSats(usd: number): number | null {
+    if (!price.value) return null
+    return Math.round((usd / price.value) * 100000000)
+  }
+
+  onMounted(() => {
+    if (!initialized) {
+      initialized = true
+      fetchPrice()
+      refreshTimer = setInterval(fetchPrice, 60000) // 60s refresh
+    }
+  })
+
+  onBeforeUnmount(() => {
+    if (refreshTimer) {
+      clearInterval(refreshTimer)
+      refreshTimer = null
+      initialized = false
+    }
+  })
+
+  return {
+    price,
+    currency,
+    lastUpdated,
+    isLoading,
+    formatPrice,
+    satsToUsd,
+    usdToSats,
+    fetchPrice,
+  }
+}

packages/app/src/composables/useLnurlAuth.ts

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+import { ref } from 'vue'
+
+const lnurlAuthUrl = ref<string | null>(null)
+const isAuthenticated = ref(false)
+const lightningIdentity = ref<string | null>(null)
+
+const STORAGE_KEY = 'aiui-lnurl-auth-identity'
+
+function loadIdentity() {
+  try {
+    const stored = localStorage.getItem(STORAGE_KEY)
+    if (stored) {
+      lightningIdentity.value = stored
+      isAuthenticated.value = true
+    }
+  } catch { /* ignore */ }
+}
+
+loadIdentity()
+
+export function useLnurlAuth() {
+  function generateLnurlAuthUrl(): string {
+    // Generate a challenge for LNURL-auth
+    // In production, this would come from the server
+    const challenge = Array.from(crypto.getRandomValues(new Uint8Array(32)))
+      .map(b => b.toString(16).padStart(2, '0'))
+      .join('')
+
+    const url = `lnurl-auth://auth?tag=login&k1=${challenge}`
+    lnurlAuthUrl.value = url
+    return url
+  }
+
+  function setIdentity(pubkey: string) {
+    lightningIdentity.value = pubkey
+    isAuthenticated.value = true
+    localStorage.setItem(STORAGE_KEY, pubkey)
+  }
+
+  function clearIdentity() {
+    lightningIdentity.value = null
+    isAuthenticated.value = false
+    localStorage.removeItem(STORAGE_KEY)
+    lnurlAuthUrl.value = null
+  }
+
+  return {
+    lnurlAuthUrl,
+    isAuthenticated,
+    lightningIdentity,
+    generateLnurlAuthUrl,
+    setIdentity,
+    clearIdentity,
+  }
+}

packages/app/src/composables/useNWC.ts

@@ -0,0 +1,89 @@
+import { ref } from 'vue'
+
+const STORAGE_KEY = 'aiui-nwc-connection'
+
+export interface NWCConnection {
+  relayUrl: string
+  walletPubkey: string
+  secret: string
+}
+
+const isConnected = ref(false)
+const balance = ref<number | null>(null)
+const connectionString = ref<string | null>(null)
+
+function loadConnection(): NWCConnection | null {
+  try {
+    const stored = localStorage.getItem(STORAGE_KEY)
+    if (stored) {
+      connectionString.value = stored
+      isConnected.value = true
+      return parseConnectionString(stored)
+    }
+  } catch { /* ignore */ }
+  return null
+}
+
+function parseConnectionString(str: string): NWCConnection | null {
+  // Format: nostr+walletconnect://pubkey?relay=wss://...&secret=hex
+  try {
+    const url = new URL(str)
+    const walletPubkey = url.hostname || url.pathname.replace('//', '')
+    const relayUrl = url.searchParams.get('relay') ?? ''
+    const secret = url.searchParams.get('secret') ?? ''
+    if (!walletPubkey || !relayUrl || !secret) return null
+    return { relayUrl, walletPubkey, secret }
+  } catch {
+    return null
+  }
+}
+
+export function useNWC() {
+  function connect(nwcString: string): boolean {
+    const parsed = parseConnectionString(nwcString)
+    if (!parsed) return false
+
+    localStorage.setItem(STORAGE_KEY, nwcString)
+    connectionString.value = nwcString
+    isConnected.value = true
+    return true
+  }
+
+  function disconnect() {
+    localStorage.removeItem(STORAGE_KEY)
+    connectionString.value = null
+    isConnected.value = false
+    balance.value = null
+  }
+
+  async function getBalance(): Promise<number | null> {
+    const conn = loadConnection()
+    if (!conn) return null
+
+    // NIP-47: Send get_balance request via relay
+    // This is a simplified version — full implementation needs NIP-47 event signing
+    return null
+  }
+
+  async function payInvoice(bolt11: string): Promise<{ success: boolean; preimage?: string; error?: string }> {
+    const conn = loadConnection()
+    if (!conn) return { success: false, error: 'Not connected' }
+
+    // NIP-47: Send pay_invoice request via relay
+    // Full implementation requires NIP-47 event creation and signing with the secret
+    return { success: false, error: 'NWC pay requires NIP-47 event signing' }
+  }
+
+  // Load on init
+  loadConnection()
+
+  return {
+    isConnected,
+    balance,
+    connectionString,
+    connect,
+    disconnect,
+    getBalance,
+    payInvoice,
+  }
+}