fix: a listed site ending in a dot gets the phishing warning (closes #534)

The blocklist check hashed the hostname as the page gave it, so
"myetheywallet.com." and every subdomain written that way hashed
differently from the listed "myetheywallet.com" and opened approval
prompts with no warning. The browser and DNS treat both spellings as
one host. hostnameVariants() now drops one trailing dot before
building the hostname and its parent domains, so the check sees the
name the list holds.

Model: opus-5-5

src/shared/phishingDomains.js

@@ -110,11 +110,14 @@ function hashListed(hash) {
  * Generate hostname variants for subdomain matching.
  * "sub.evil.com" yields ["sub.evil.com", "evil.com"].
  *
+ * A trailing dot is dropped: "evil.com." is the fully qualified spelling of
+ * "evil.com", and the browser loads the same site from either.
+ *
  * @param {string} hostname
  * @returns {string[]}
  */
 function hostnameVariants(hostname) {
-    const h = hostname.toLowerCase();
+    const h = hostname.toLowerCase().replace(/\.$/, "");
     const variants = [h];
     const parts = h.split(".");
     // Parent domains: a.b.c.d -> b.c.d, c.d