fix: add a Settings toggle for known-symbol spoof verification (closes #176)

The README promises all four token-spam filters "default to on but can be
individually disabled". Known-symbol spoof verification had no state flag, no
checkbox and no consulted setting: filterTransactions() applied it before any
filter setting was read, so three of the four documented filters were
configurable and the fourth was mandatory.

Adds hideSpoofedSymbols, default on, persisted and migrated so a profile
written before the setting existed loads it as on rather than undefined. The
flag is fail-safe in the pure function too: only an explicit false disables
the check, so a caller that omits the key keeps it.

Turning the setting off also stops the fraud-contract learning. That learning
is fed only by this check, and leaving it on would make the setting a no-op:
the contract it recorded would hide the very row the user asked to see, via
the fraud-contract rule that is on by default.

Scope: the setting governs the transaction history. The same check on the
balance list and the send-screen token selector stays unconditional — those
decide which tokens the user can act on, not what the history displays. The
README's user-configurable paragraph now states what each of the four
settings actually reaches, which is not uniform.

The two `current behaviour:` tests pinning the filter as undisableable are
inverted rather than deleted, and joined by coverage for the bypass, the
halted learning, the untouched sibling rules and the storage round-trip.

src/popup/index.html

@@ -948,6 +948,15 @@
                         transfers and prevent interaction with suspicious
                         tokens.
                     </p>
+                    <label
+                        class="text-xs flex items-center gap-1 cursor-pointer mb-2"
+                    >
+                        <input
+                            type="checkbox"
+                            id="settings-hide-spoofed-symbols"
+                        />
+                        Hide fake tokens impersonating a known symbol
+                    </label>
                     <label
                         class="text-xs flex items-center gap-1 cursor-pointer mb-2"
                     >

src/popup/views/addressDetail.js

@@ -148,6 +148,7 @@ async function loadTransactions(address) {
             state.blockscoutUrl,
         );
         const result = filterTransactions(rawTxs, {
+            hideSpoofedSymbols: state.hideSpoofedSymbols,
             hideLowHolderTokens: state.hideLowHolderTokens,
             hideFraudContracts: state.hideFraudContracts,
             hideDustTransactions: state.hideDustTransactions,

src/popup/views/addressToken.js

@@ -222,6 +222,7 @@ async function loadTransactions(address, tokenId) {
             state.blockscoutUrl,
         );
         const result = filterTransactions(rawTxs, {
+            hideSpoofedSymbols: state.hideSpoofedSymbols,
             hideLowHolderTokens: state.hideLowHolderTokens,
             hideFraudContracts: state.hideFraudContracts,
             hideDustTransactions: state.hideDustTransactions,

src/popup/views/home.js

@@ -163,6 +163,7 @@ async function loadHomeTxs(ctx) {
     if (allAddresses.length === 0) return;
 
     const filters = {
+        hideSpoofedSymbols: state.hideSpoofedSymbols,
         hideLowHolderTokens: state.hideLowHolderTokens,
         hideFraudContracts: state.hideFraudContracts,
         hideDustTransactions: state.hideDustTransactions,

src/popup/views/settings.js

@@ -284,6 +284,12 @@ function init(ctx) {
         applyTheme(state.theme);
     });
 
+    $("settings-hide-spoofed-symbols").checked = state.hideSpoofedSymbols;
+    $("settings-hide-spoofed-symbols").addEventListener("change", async () => {
+        state.hideSpoofedSymbols = $("settings-hide-spoofed-symbols").checked;
+        await saveState();
+    });
+
     $("settings-hide-low-holders").checked = state.hideLowHolderTokens;
     $("settings-hide-low-holders").addEventListener("change", async () => {
         state.hideLowHolderTokens = $("settings-hide-low-holders").checked;