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/symbolSpoof.test.js

@@ -485,8 +485,12 @@ describe("surface 2: the Send token selector", () => {
     function render(tokenBalances) {
         select = { innerHTML: "", children: [] };
         select.appendChild = (child) => select.children.push(child);
+        const elements = {
+            "send-token": select,
+            "send-tokens-note": { classList: { toggle: () => {} } },
+        };
         globalThis.document = {
-            getElementById: (id) => (id === "send-token" ? select : null),
+            getElementById: (id) => elements[id] || null,
             createElement: () => ({ value: "", textContent: "" }),
         };
         renderSendTokenSelect({
@@ -582,12 +586,14 @@ describe("surface 3: the balance list", () => {
     // 1,000-holder floor and was listed as a holding named ETH.
     test("a fake ETH token clearing the holder floor is filtered", async () => {
         respondWith([fakeEthItem()]);
-        expect(await fetchTokenBalances(HOLDER, BLOCKSCOUT, [])).toEqual([]);
+        expect(await fetchTokenBalances(HOLDER, BLOCKSCOUT, true, [])).toEqual(
+            [],
+        );
     });
 
     test("tracking the fake token manually does not admit it either", async () => {
         respondWith([fakeEthItem({ holders_count: "0" })]);
-        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, [
+        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, true, [
             { address: FAKE_ETH_CONTRACT },
         ]);
         expect(balances).toEqual([]);
@@ -597,12 +603,16 @@ describe("surface 3: the balance list", () => {
     // their belief about what they own, and it renders the symbol into HTML.
     test("a padded fake ETH token is filtered too", async () => {
         respondWith([fakeEthItem({ symbol: " ETH " })]);
-        expect(await fetchTokenBalances(HOLDER, BLOCKSCOUT, [])).toEqual([]);
+        expect(await fetchTokenBalances(HOLDER, BLOCKSCOUT, true, [])).toEqual(
+            [],
+        );
     });
 
     test("a fake ETH token padded with a no-break space is filtered", async () => {
         respondWith([fakeEthItem({ symbol: NBSP + "ETH" + NBSP })]);
-        expect(await fetchTokenBalances(HOLDER, BLOCKSCOUT, [])).toEqual([]);
+        expect(await fetchTokenBalances(HOLDER, BLOCKSCOUT, true, [])).toEqual(
+            [],
+        );
     });
 
     // The false-positive direction on the surface that matters most: a real
@@ -617,7 +627,7 @@ describe("surface 3: the balance list", () => {
                 decimals: "6",
             }),
         ]);
-        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, []);
+        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, true, []);
         expect(balances).toHaveLength(1);
         expect(balances[0].symbol).toBe(" USDC ");
     });
@@ -631,7 +641,7 @@ describe("surface 3: the balance list", () => {
                 decimals: "6",
             }),
         ]);
-        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, []);
+        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, true, []);
         expect(balances).toHaveLength(1);
         expect(balances[0].symbol).toBe("USDC");
     });
@@ -642,7 +652,9 @@ describe("surface 3: the balance list", () => {
     // before the symbol rule is consulted.
     test("a non-ERC-20 row claiming ETH never reaches the symbol rule", async () => {
         respondWith([fakeEthItem({ type: "ERC-721" })]);
-        expect(await fetchTokenBalances(HOLDER, BLOCKSCOUT, [])).toEqual([]);
+        expect(await fetchTokenBalances(HOLDER, BLOCKSCOUT, true, [])).toEqual(
+            [],
+        );
     });
 
     // The adjacent finding from the same review as issue #260: the type gate
@@ -660,16 +672,20 @@ describe("surface 3: the balance list", () => {
                 decimals: "6",
             }),
         ]);
-        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, []);
+        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, true, []);
         expect(balances).toHaveLength(1);
         expect(balances[0].symbol).toBe("USDC");
     });
 
     test("case insensitivity does not admit another token type", async () => {
         respondWith([fakeEthItem({ type: "erc-721" })]);
-        expect(await fetchTokenBalances(HOLDER, BLOCKSCOUT, [])).toEqual([]);
+        expect(await fetchTokenBalances(HOLDER, BLOCKSCOUT, true, [])).toEqual(
+            [],
+        );
         respondWith([fakeEthItem({ type: "ERC-20-EXTRA" })]);
-        expect(await fetchTokenBalances(HOLDER, BLOCKSCOUT, [])).toEqual([]);
+        expect(await fetchTokenBalances(HOLDER, BLOCKSCOUT, true, [])).toEqual(
+            [],
+        );
     });
 
     // The money test: the user holds real ETH and has been airdropped a fake
@@ -682,6 +698,7 @@ describe("surface 3: the balance list", () => {
             [{ addresses: [addr] }],
             "https://rpc.example.invalid",
             BLOCKSCOUT,
+            true,
             [],
             "mainnet",
         );