fix: Blockscout and Etherscan lookups are off until the user turns them on (closes #668)

Out of the box the wallet sent the user's addresses to Blockscout for history
and token lookups. It sent each recipient to Etherscan for its label. Two
settings, "Use Blockscout" and "Check recipients on Etherscan", now gate those
requests. Both are off in a new install and offered unticked on Welcome and in
Settings. While one is off, the screens that relied on it say so in a plain
line. The balance refresh and the Etherscan check read the stored setting. An
open popup takes a change another page saved and draws its screens again. While
"Use Blockscout" is off, no address keeps an untracked token. ENS lookups ask
only the RPC endpoint.

Model: opus-5-5

tests/stateRecovery.test.js

@@ -523,13 +523,15 @@ describe("a garbage value in a field the gate does not check", () => {
     });
 
     test("a malformed tokenBalances entry is dropped, and the wallet and its address survive", async () => {
-        const env = await bootPopup(
-            profileWithTokenBalances([
-                null,
-                42,
-                { address: TOKEN_ADDRESS, symbol: "AAA", balance: "2.0" },
-            ]),
-        );
+        // "Use Blockscout" is on, or the boot's balance refresh drops the
+        // well-formed entry too: the user has not tracked its token.
+        const profile = profileWithTokenBalances([
+            null,
+            42,
+            { address: TOKEN_ADDRESS, symbol: "AAA", balance: "2.0" },
+        ]);
+        profile.useBlockscout = true;
+        const env = await bootPopup(profile);
 
         const stored = env.storage.read("autistmask");
         expect(stored.wallets[0].encryptedSecret).toBe("encrypted-secret-1");