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. It is exported as
applyEnrichment, and tests/applyEnrichment.test.js fails when the committed
list differs from what it writes from the committed data. make enrich-tokens
and make apply-enrichment run them. script/check-censored allows the MUSD
token's on-chain name in the data file.

Model: opus-5-5

tests/applyEnrichment.test.js

@@ -0,0 +1,19 @@
+// The token names and URLs in src/shared/tokenList.js are written from
+// script/lib/token-enrichment.json by script/lib/apply-enrichment.js
+// (`make apply-enrichment`). The committed list must be exactly what it writes
+// from the committed data, so the list, the data and the script cannot drift
+// apart.
+
+const fs = require("fs");
+const path = require("path");
+
+const enrichment = require("../script/lib/token-enrichment.json");
+const { applyEnrichment } = require("../script/lib/apply-enrichment");
+
+test("src/shared/tokenList.js is what make apply-enrichment writes from the committed data", () => {
+    const committed = fs.readFileSync(
+        path.join(__dirname, "..", "src/shared/tokenList.js"),
+        "utf8",
+    );
+    expect(applyEnrichment(committed, enrichment)).toBe(committed);
+});