chore: bring the token-list enrichment tooling into script/lib (closes #495)

The two node programs and the data file from f7a2437 regenerate the name and
url of each token in src/shared/tokenList.js. They are now CommonJS under
script/lib/, find their files from their own location, and read
ethereum-lists at a pinned commit. The apply step also rewrites an entry that
already has a name and url, so it runs on the current list; on the committed
data it leaves the list unchanged. make enrich-tokens and make
apply-enrichment run them, and README.md names both targets. The data file
carries the MUSD token's on-chain name, so script/check-censored allows that
one literal there too.

Model: opus-5-5

src/background/index.js

@@ -633,9 +633,8 @@ function isExtensionSender(sender) {
 // had refused.
 //
 // TX and sign approvals do not decide here. They stay pending across a
-// disconnect. When their window closes, the windows.onRemoved listener below
-// rejects them, unless an approved attempt is still running, in which case
-// that attempt answers the page.
+// disconnect — the user can reopen the toolbar popup — and are rejected by the
+// windows.onRemoved listener below.
 runtime.onConnect.addListener((port) => {
     if (port.name.startsWith("approval:")) {
         const id = port.name.split(":")[1];
@@ -663,9 +662,7 @@ runtime.onConnect.addListener((port) => {
             const approval = pendingApprovals[id];
             if (approval) {
                 if (approval.type === "tx" || approval.type === "sign") {
-                    // When its window closes, windows.onRemoved rejects it,
-                    // unless an approved attempt is still running, in which
-                    // case that attempt answers the page.
+                    // Keep pending — user can reopen the toolbar popup
                     return;
                 }
                 settleApproval(id, { approved: false, remember: false });