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

README.md

@@ -728,6 +728,7 @@ of it.
     - Blockscout API: endpoint URL input + "Save" button (validated against
       `/stats` before being saved)
     - Token Spam Protection:
+        - "Hide fake tokens impersonating a known symbol" checkbox
         - "Hide tokens with fewer than 1,000 holders" checkbox
         - "Hide transactions from detected fraud contracts" checkbox
         - "Hide dust transactions below N gwei" checkbox + threshold input
@@ -1116,7 +1117,19 @@ indexes it as a real token transfer.
   a spoof and filtered from display. The fake "Ethereum" token in the attack
   above used symbol "ETH" from contract
   `0xD05339f9Ea5ab9d9F03B9d57F671d2abD1F55c82`, which does not match the known
-  WETH contract — so it would be caught by this check.
+  WETH contract — so it would be caught by this check. Detecting a spoof is also
+  what adds a contract to the fraud contract blocklist below; that is the only
+  thing that populates it. In the transaction history the check is the "Hide
+  fake tokens impersonating a known symbol" setting, on by default; with it off,
+  spoofed transfers are shown and no new blocklist entries are learned from
+  them. The send-screen token selector applies the same check unconditionally,
+  because it decides which tokens the user can act on rather than what the
+  history displays. The balance list applies it unconditionally too, but not
+  identically: it exempts symbols that `KNOWN_SYMBOLS` maps to `null`, and
+  `"ETH"` is the only one. So the fake "Ethereum" token above is filtered from
+  the transaction history and from the send selector, but a fake-`ETH` ERC-20
+  that clears the balance list's own 1,000-holder floor — or that the user
+  tracked manually — is still shown in the balance list.
 
 - **Low-holder token filtering**: Token transfers from ERC-20 contracts with
   fewer than 1,000 holders are hidden from transaction history by default.
@@ -1146,11 +1159,19 @@ indexes it as a real token transfer.
   about. The threshold is user-configurable in Settings; a threshold of `0`
   hides nothing, exactly as clearing the checkbox does.
 
-- **User-configurable**: All of the above filters (known symbol verification,
-  low-holder threshold, fraud contract blocklist, dust threshold) are settings
-  that default to on but can be individually disabled by the user. AutistMask is
-  designed as a sharp tool — users who understand the risks can configure the
-  wallet to show everything unfiltered, unix-style.
+- **User-configurable**: All four filters (known symbol verification, low-holder
+  threshold, fraud contract blocklist, dust threshold) are settings that default
+  to on but can be individually disabled by the user. AutistMask is designed as
+  a sharp tool — users who understand the risks can configure the wallet to show
+  everything unfiltered, unix-style. All four settings govern the transaction
+  history; what else each one reaches varies. The known-symbol check also runs
+  unconditionally on the send-screen token selector, and on the balance list
+  except for symbols mapped to `null` (`"ETH"` alone), which the balance list
+  does not filter. The fraud contract blocklist is applied unconditionally on
+  that selector and is not consulted by the balance list at all. The low-holder
+  setting also gates the send selector, while the balance list's own
+  1,000-holder floor is unconditional (see Data Model). The dust threshold
+  applies to the transaction history alone.
 
 #### Phishing Domain Protection