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;

src/shared/state.js

@@ -21,6 +21,7 @@ const DEFAULT_STATE = {
     deniedSites: {},
     rememberSiteChoice: true,
     showZeroBalanceTokens: true,
+    hideSpoofedSymbols: true,
     hideLowHolderTokens: true,
     hideFraudContracts: true,
     hideDustTransactions: true,
@@ -61,6 +62,7 @@ async function saveState() {
         deniedSites: state.deniedSites,
         rememberSiteChoice: state.rememberSiteChoice,
         showZeroBalanceTokens: state.showZeroBalanceTokens,
+        hideSpoofedSymbols: state.hideSpoofedSymbols,
         hideLowHolderTokens: state.hideLowHolderTokens,
         hideFraudContracts: state.hideFraudContracts,
         hideDustTransactions: state.hideDustTransactions,
@@ -112,6 +114,12 @@ async function loadState() {
             saved.showZeroBalanceTokens !== undefined
                 ? saved.showZeroBalanceTokens
                 : true;
+        // A profile written before this setting existed has no key for it.
+        // It is a safety filter, so absent must load as on, not as undefined.
+        state.hideSpoofedSymbols =
+            saved.hideSpoofedSymbols !== undefined
+                ? saved.hideSpoofedSymbols
+                : true;
         state.hideLowHolderTokens =
             saved.hideLowHolderTokens !== undefined
                 ? saved.hideLowHolderTokens

src/shared/transactions.js

@@ -254,10 +254,17 @@ function filterTransactions(txs, filters = {}) {
     );
     const newFraud = [];
     const filtered = [];
+    // Fail-safe, unlike the three flags below: this one is off only when the
+    // caller says so explicitly, so a caller that omits the key keeps the
+    // check rather than silently losing it.  The setting also governs the
+    // blocklist learning below, which exists only to serve this check —
+    // leaving learning on while the check is off would re-hide the very rows
+    // the user asked to see, through the fraud-contract rule.
+    const hideSpoofed = filters.hideSpoofedSymbols !== false;
 
     for (const tx of txs) {
-        // Always filter spoofed known symbols and record the fraud contract
-        if (isSpoofedSymbol(tx)) {
+        // Filter spoofed known symbols and record the fraud contract
+        if (hideSpoofed && isSpoofedSymbol(tx)) {
             if (tx.contractAddress && !fraudSet.has(tx.contractAddress)) {
                 fraudSet.add(tx.contractAddress);
                 newFraud.push(tx.contractAddress);