Support WalletConnect multi-chain sessions

[YeungKC]

Summary

• Approve WalletConnect sessions with all available EVM, Solana, and Bitcoin namespaces instead of a single selected chain.
• Add Bitcoin CAIP-2 namespace support for getAccountAddresses and signMessage without advertising unsupported transfer or PSBT methods.
• Update session proposal display and account switching to use chain-specific addresses.
• Add namespace tests for multi-address support and blank-address filtering.

Validation

• git diff --check
• ./gradlew :app:testOtherChannelDebugUnitTest --tests one.mixin.android.tip.wc.internal.WalletConnectNamespaceTest

[Copilot]

Pull request overview

This PR expands the app’s WalletConnect v2 support to multi-chain sessions by approving all supported namespaces/addresses (EVM + Solana + Bitcoin) instead of a single selected chain, and adds initial Bitcoin namespace handling for address discovery and message signing.

Changes:

• Generate approved namespaces from all available wallet addresses (EVM/Solana/Bitcoin) and update session account switching to be chain-aware.
• Add Bitcoin bip122 namespace support for getAccountAddresses and signMessage requests, plus related models.
• Update session proposal display/account selection and add unit tests for multi-address namespace building and blank-address filtering.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
app/src/test/java/one/mixin/android/tip/wc/internal/WalletConnectNamespaceTest.kt	Adds tests for multi-namespace generation and blank-address filtering.
app/src/main/java/one/mixin/android/web3/js/Web3Signer.kt	Switches WalletConnect account updates to pass a full address bundle (EVM/Solana/BTC).
app/src/main/java/one/mixin/android/ui/tip/wc/WalletConnectBottomSheetViewModel.kt	Adds a PIN verification helper for V2 session proposals that no longer require deriving a chain private key.
app/src/main/java/one/mixin/android/ui/tip/wc/WalletConnectBottomSheetDialogFragment.kt	Updates proposal UI/account text and approval flow for multi-chain sessions.
app/src/main/java/one/mixin/android/tip/wc/WalletConnectV2.kt	Approves sessions with all supported namespaces; adds BTC request parsing/approval; updates account switching to be chain-aware.
app/src/main/java/one/mixin/android/tip/wc/internal/WcBitcoin.kt	Introduces request/response models for WalletConnect Bitcoin methods.
app/src/main/java/one/mixin/android/tip/wc/internal/Method.kt	Adds BTC method constants and supported method lists.
app/src/main/java/one/mixin/android/tip/wc/internal/Chain.kt	Adds BTC CAIP-2 namespace/reference and introduces multi-address namespace generation helpers.

Comments suppressed due to low confidence (1)

app/src/main/java/one/mixin/android/tip/wc/internal/Chain.kt:91

• String.getChain() currently matches EVM chains using chainReference (e.g. "1", "8453") but WalletConnect proposal chains are CAIP-2 strings (e.g. "eip155:1"). This makes c.getChain() return null for EVM proposals, leaving the UI defaulting to Chain.Ethereum even when a different EVM chain was requested.

internal fun String.getChain(): Chain? {
    return when (this) {
        Chain.Ethereum.chainReference -> Chain.Ethereum
        Chain.Base.chainReference -> Chain.Base
        Chain.Arbitrum.chainReference -> Chain.Arbitrum

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