Keep Cc recipients in reply-all

* fix: populate window._myEmailAddress from the active email account

* fix: keep Cc recipients in reply-all when own address is empty or unknown

* test: cover reply-all recipient building (issue #360)

static/js/emailLibrary/replyRecipients.js

@@ -0,0 +1,25 @@
+// static/js/emailLibrary/replyRecipients.js
+//
+// Pure helpers for building reply-all recipient lists. No DOM, no fetch,
+// no shared state — safe to import anywhere and to unit-test under node.
+
+// Extract the bare email from "Name <email@x>" or a plain "email@x".
+export function extractEmail(addr) {
+  const m = (addr || '').match(/<([^>]+)>/);
+  return (m ? m[1] : (addr || '')).trim().toLowerCase();
+}
+
+// Reply-all CC = everyone on the original To + Cc, minus ourselves, with the
+// original "Name <email>" form preserved.
+//
+// `myAddress` empty/unknown ⇒ no exclusion. Comparing by exact extracted email
+// (not a substring `includes`) is what fixes issue #360: an empty self address
+// made `"...".includes("")` true for every recipient, so reply-all dropped the
+// entire Cc list and kept only the original sender.
+export function buildReplyAllCc(data, myAddress) {
+  const me = (myAddress || '').toLowerCase();
+  const split = (s) => (s || '').split(',').map((x) => x.trim()).filter(Boolean);
+  return [...split(data && data.to), ...split(data && data.cc)]
+    .filter((addr) => !me || extractEmail(addr) !== me)
+    .join(', ');
+}