fix: recognize BIP21 bitcoin: URIs when scanning a QR code

Confirmed live: sending BTC back out via QR-scanning an external wallet's/
exchange's receive address failed with a generic "QR can't be decoded"
error. Root cause: the QR decoder only ever recognized two shapes -
substrate:<address>:<pubkey> triples and bare address strings - neither of
which matches the bitcoin:<address>?amount=... BIP21 URI most wallets and
exchanges generate for a BTC address. Adds BitcoinUriQrFormat, tried
alongside the existing formats, that strips the scheme and query string
before validating the address the normal way.

runtime/src/main/java/io/novafoundation/nova/runtime/multiNetwork/qr/BitcoinUriQrFormat.kt

@@ -0,0 +1,36 @@
+package io.novafoundation.nova.runtime.multiNetwork.qr
+
+import io.novasama.substrate_sdk_android.encrypt.qr.PublicQrFormat
+import io.novasama.substrate_sdk_android.encrypt.qr.QrFormat
+
+private const val BITCOIN_URI_SCHEME = "bitcoin:"
+
+/**
+ * BIP21 URI (`bitcoin:<address>?amount=...&label=...`) - the standard QR payload most wallets/exchanges generate
+ * for a Bitcoin receive address. Neither `SubstrateQrFormat` (expects a `substrate:<address>:<pubkey>` triple)
+ * nor `AddressQrFormat` (treats the whole QR content as a bare address) recognize this, so scanning an external
+ * wallet's or exchange's BTC address QR failed outright with the generic "QR can't be decoded" error - confirmed
+ * live against a real BTC withdrawal QR.
+ */
+class BitcoinUriQrFormat(
+    private val addressValidator: (String) -> Boolean
+) : PublicQrFormat {
+
+    override fun encode(payload: PublicQrFormat.Payload): String {
+        return "$BITCOIN_URI_SCHEME${payload.address}"
+    }
+
+    override fun decode(qrContent: String): PublicQrFormat.Payload {
+        if (!qrContent.startsWith(BITCOIN_URI_SCHEME, ignoreCase = true)) {
+            throw QrFormat.InvalidFormatException("Not a bitcoin: URI")
+        }
+
+        val address = qrContent.substring(BITCOIN_URI_SCHEME.length).substringBefore('?')
+
+        return if (addressValidator(address)) {
+            PublicQrFormat.Payload(address = address)
+        } else {
+            throw QrFormat.InvalidFormatException("Supplied bitcoin: URI has an invalid address")
+        }
+    }
+}

runtime/src/main/java/io/novafoundation/nova/runtime/multiNetwork/qr/MultiChainQrSharingFactory.kt

@@ -8,10 +8,12 @@ class MultiChainQrSharingFactory {
 
     fun create(addressValidator: (String) -> Boolean): QrSharing {
         val substrateFormat = SubstrateQrFormat()
+        val bitcoinUriFormat = BitcoinUriQrFormat(addressValidator)
         val onlyAddressFormat = AddressQrFormat(addressValidator)
 
         val formats = listOf(
             substrateFormat,
+            bitcoinUriFormat,
             onlyAddressFormat
         )