fix(bridge): cp-7.67.0 display block explorer tx link for Popular networks in transaction details (#26659)

## **Description**

`getBlockExplorerForChain()` in `TransactionDetails` only resolved block
explorer URLs for hardcoded built-in networks (Mainnet, Linea, Sepolia)
and user-added custom RPC networks. Popular networks (Arbitrum, Polygon,
BNB Chain, etc.) are neither — they aren't stored in
`networkConfigurations` — so the method fell through to
`NO_RPC_BLOCK_EXPLORER`, hiding the "View on X" link entirely.

The fix adds a `PopularList` lookup as a fallback, matching the pattern
already used correctly in useBlockExplorer.ts.

## **Changelog**

CHANGELOG entry: Fixed a bug where transactions on popular networks
(Arbitrum, Polygon, BNB Chain, etc.) were missing the block explorer
link in transaction details

## **Related issues**

Fixes: #26419

## **Manual testing steps**

```gherkin
Feature: Block explorer link in transaction details

  Scenario: user views a transaction from a Popular network
    Given the user has transactions on Arbitrum, Polygon, or BNB Chain
    And the activity feed is filtered by "Popular networks"

    When user taps a confirmed transaction from one of those networks
    Then a "View on Arbiscan" / "View on Polygonscan" / "View on Bscscan" link appears
    And tapping it opens the correct block explorer tx URL in the webview

  Scenario: user views a transaction on Ethereum Mainnet
    Given the user has transactions on Ethereum Mainnet
    When user taps a confirmed transaction
    Then a "View on Etherscan" link still appears (regression check)
```

## **Screenshots/Recordings**

`~`

### **Before**


https://github.com/user-attachments/assets/0b15c664-e62e-4811-94f6-e12687454025

### **After**


https://github.com/user-attachments/assets/8c71420a-f95a-4ebe-ba4c-dedd7cfebc0e

## **Pre-merge author checklist**

- [x] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask Mobile
Coding
Standards](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
- [x] I've included tests if applicable
- [ ] I've documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] I've applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [x] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [x] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.


<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Low risk UI fix that only changes how the transaction details screen
resolves a block explorer URL, with added test coverage to prevent
regressions.
> 
> **Overview**
> Fixes missing **“View on …”** links in `TransactionDetails` for
*popular networks* that aren’t present in `networkConfigurations` by
falling back to `PopularList` to resolve `rpcPrefs.blockExplorerUrl`.
> 
> Adds unit tests ensuring the correct explorer link text/URL is
produced for Arbitrum, Polygon, and BNB Chain, alongside existing
mainnet/custom-network coverage.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
0e7e142. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: vinnyhoward

app/components/UI/TransactionElement/TransactionDetails/index.js

@@ -66,6 +66,7 @@ import {
 } from '../../../../constants/urls';
 import { CHAIN_IDS } from '@metamask/transaction-controller';
 import TagBase from '../../../../component-library/base-components/TagBase';
+import { PopularList } from '../../../../util/networks/customNetworks';
 
 const createStyles = (colors) =>
   StyleSheet.create({
@@ -199,6 +200,16 @@ class TransactionDetails extends PureComponent {
       blockExplorer = SEPOLIA_BLOCK_EXPLORER;
     }
 
+    // Check PopularList for additional networks (e.g. Arbitrum, Polygon, BNB)
+    if (blockExplorer === NO_RPC_BLOCK_EXPLORER) {
+      const popularNetwork = PopularList.find(
+        (network) => network.chainId === txChainId,
+      );
+      if (popularNetwork?.rpcPrefs?.blockExplorerUrl) {
+        blockExplorer = popularNetwork.rpcPrefs.blockExplorerUrl;
+      }
+    }
+
     // Check for non-EVM chain block explorer
     if (isNonEvmChainId(chainId)) {
       blockExplorer = findBlockExplorerForNonEvmChainId(chainId);

app/components/UI/TransactionElement/TransactionDetails/index.test.tsx

@@ -348,6 +348,57 @@ describe('TransactionDetails', () => {
     });
   });
 
+  it('should display explorer link for arbitrum (popular network not in networkConfigurations)', () => {
+    arrangeActAssertBlockExplorerTest({
+      overrideMocks: (mocks) => {
+        mocks.mockState.engine.backgroundState.NetworkController =
+          mockNetworkState({
+            chainId: '0x1',
+            id: 'mainnet',
+            nickname: 'Ethereum Mainnet',
+            ticker: 'ETH',
+          });
+        mocks.mockProps.networkId = '0xa4b1';
+      },
+      buttonText: 'View on Arbiscan',
+      expectedUrl: 'https://arbiscan.io/tx/0x3',
+    });
+  });
+
+  it('should display explorer link for polygon (popular network not in networkConfigurations)', () => {
+    arrangeActAssertBlockExplorerTest({
+      overrideMocks: (mocks) => {
+        mocks.mockState.engine.backgroundState.NetworkController =
+          mockNetworkState({
+            chainId: '0x1',
+            id: 'mainnet',
+            nickname: 'Ethereum Mainnet',
+            ticker: 'ETH',
+          });
+        mocks.mockProps.networkId = '0x89';
+      },
+      buttonText: 'View on Polygonscan',
+      expectedUrl: 'https://polygonscan.com/tx/0x3',
+    });
+  });
+
+  it('should display explorer link for bnb chain (popular network not in networkConfigurations)', () => {
+    arrangeActAssertBlockExplorerTest({
+      overrideMocks: (mocks) => {
+        mocks.mockState.engine.backgroundState.NetworkController =
+          mockNetworkState({
+            chainId: '0x1',
+            id: 'mainnet',
+            nickname: 'Ethereum Mainnet',
+            ticker: 'ETH',
+          });
+        mocks.mockProps.networkId = '0x38';
+      },
+      buttonText: 'View on Bscscan',
+      expectedUrl: 'https://bscscan.com/tx/0x3',
+    });
+  });
+
   it('should render `Batched transactions` tag if there are nested transactions', async () => {
     const { getByText } = renderComponent({
       state: initialState,