fix: name a tracked or explorer-known token instead of "Unknown token" (closes #323)

The approval and transaction-status screens read a token's scale from the
bundled list, the tokens the user tracks, then the block explorer, but read
its symbol from the bundled list alone. A token the user added by hand was
scaled correctly yet labelled "Unknown token", and a non-bundled ERC-20 was
carried onto the wait screen as ETH.

resolveTokenSymbol() now draws the symbol through the same sources and
precedence as the scale, and the ERC-20 and Uniswap swap lines both use it. A
tracked or explorer-reported name stays subject to the spoof rule, so it
cannot claim a bundled or native ticker.

Folds in #354.

Model: opus-4-8

tests/approvalAmount.test.js

@@ -143,16 +143,18 @@ describe("decodeCalldata amount", () => {
         state.trackedTokens = [
             { address: NOVEL_TOKEN, symbol: "NOVEL", decimals: 6 },
         ];
+        // The tracked entry supplies both: the scale (5000.0000) and, since
+        // issue #323, the symbol that the scale is counted in.
         expect(
             amountLine(transferData(FIVE_THOUSAND_AT_SIX), NOVEL_TOKEN),
-        ).toBe("5000.0000");
+        ).toBe("5000.0000 NOVEL");
     });
 
     test("transfer priced off the explorer's decimals shows the true quantity", () => {
         state.wallets = walletsHolding(NOVEL_TOKEN, "6");
         expect(
             amountLine(transferData(FIVE_THOUSAND_AT_SIX), NOVEL_TOKEN),
-        ).toBe("5000.0000");
+        ).toBe("5000.0000 NOVEL");
     });
 
     test("transfer of an unknown-decimals token shows base units, not a number", () => {
@@ -172,7 +174,7 @@ describe("decodeCalldata amount", () => {
             { address: NOVEL_TOKEN, symbol: "NOVEL", decimals: 6 },
         ];
         expect(amountLine(approveData(FIVE_THOUSAND_AT_SIX), NOVEL_TOKEN)).toBe(
-            "5000.0000",
+            "5000.0000 NOVEL",
         );
     });