AGPL source offer and name cleanup

Every build writes the exact source it was built from, uncommitted work and
new files included, as source.tar.gz next to the app, named after that tree.
Docker builds, which have no git, pack the build context and name it by a
hash of its files. The sign-in page and Settings > About link to it instead of
a repository that can drift.

What users, operators and packagers see no longer names the upstream server:
- interface text, in all nine catalogues, with a token-session line for
  Security;
- server messages;
- the settings, now MAIL_SERVER_URL, MAIL_SERVERS_FILE, ADMIN_URL and
  MAIL_SERVER_FOLLOW_ADVERTISED_URLS, and mail-servers.example.json;
- the Tenants notice, which is gone;
- the README, CONTRIBUTING and SECURITY.

ihasmail's own FEATURES, KNOWN-ISSUES and ROADMAP stay with public ihasmail,
and INBUXA.md is folded into the README.

server/src/mock/directory.ts

@@ -226,7 +226,7 @@ export function createDirectory(opts: Options) {
       push(4, "Counter", "queue.report-queued", h % 4 === 1 ? 2 : 0);
     }
   }
-  const applications: Obj[] = [{ id: "app1", description: "Stalwart Web Interface", enabled: true, urlPrefix: { "/admin": true, "/account": true } }];
+  const applications: Obj[] = [{ id: "app1", description: "Web Interface", enabled: true, urlPrefix: { "/admin": true, "/account": true } }];
 
   /** Tenants: a name, limits, and whatever names them in its memberTenantId. */
   const tenants: Obj[] = [

server/src/mock/index.ts

@@ -1,7 +1,7 @@
 /**
  * A tiny in-memory JMAP server that mimics the subset of Stalwart that ihasmail
  * uses. For local development and demos only:  `npm run mock` then point the
- * server at it with STALWART_URL=http://127.0.0.1:8788 (user: demo / pass: demo).
+ * server at it with MAIL_SERVER_URL=http://127.0.0.1:8788 (user: demo / pass: demo).
  */
 import { createServer, type IncomingMessage, type ServerResponse } from "node:http";
 import { parseOtpauthUrl, verifyTotp } from "../totp.js";
@@ -205,7 +205,7 @@ export const server = createServer(async (req, res) => {
   res.end(JSON.stringify({ error: "not found" }));
 }).listen(PORT, "127.0.0.1", () => {
   console.log(`[mock-stalwart] listening on http://127.0.0.1:${PORT}  (login: ${USER} / ${PASS})`);
-  console.log(`[mock-stalwart] run the app with: STALWART_URL=http://127.0.0.1:${PORT} npm run dev`);
+  console.log(`[mock-stalwart] run the app with: MAIL_SERVER_URL=http://127.0.0.1:${PORT} npm run dev`);
 });
 
 // Periodically inject a new inbox email to demo push