AGPL source offer, notices and name cleanup

Every build writes the exact tree it was built from, uncommitted work
included, as source.tar.gz next to the app, and names that tree. The sidebar,
user menu, sign-in card and version tooltip link to it.

Coffey Labs' copyright line is added below Stalwart Labs' in every inherited
file changed, and the new files carry Coffey Labs' alone.

The upgrade prompt and its links are gone, the edition tooltip is neutral,
storage keys and the package description are INBUXA's own, and the README
states the lineage once, in the fine print.

src/i18n/en.json

@@ -131,13 +131,7 @@
     "seconds": "Seconds"
   },
   "enterprise": {
-    "featureDisabled": "This feature requires an Enterprise license.",
-    "trialTitle": "Unlock Enterprise Features",
-    "trialDescription": "Get access to advanced features including multi-tenancy, AI-powered spam filtering, alerts, and more.",
-    "trialButton": "Start 30-Day Free Trial",
-    "requestTrial": "Request a free trial to unlock this feature.",
-    "ossHidden": "This feature is not available in the open-source edition.",
-    "whyNotFree": "Why is this not free?"
+    "featureDisabled": "This feature isn't available on this server."
   },
   "errorBoundary": {
     "title": "Something went wrong",
@@ -299,7 +293,7 @@
   },
   "logo": {
     "alt": "Logo",
-    "stalwartAlt": "INBUXA"
+    "inbuxaAlt": "INBUXA"
   },
   "logout": "Logout",
   "version": {
@@ -378,12 +372,15 @@
     "traceNotFound": "Trace not found",
     "valuePlaceholder": "Value..."
   },
-  "tryEnterprise": "Try Enterprise",
   "userMenu": "User menu",
   "view": {
     "couldNotResolve": "Could not resolve object",
     "failedToLoad": "Failed to load",
     "noGetResponse": "No get response",
     "objectNotFound": "Object not found"
+  },
+  "source": {
+    "download": "Source code of this version ({{id}}), AGPL-3.0",
+    "menu": "Source code (AGPL-3.0)"
   }
 }