feat: e-mail, password reset and shareable links for images and collections

Mail goes out through the account's own mailbox (SMTP) rather than a sending
service: the domain lives there anyway, so SPF and DKIM line up by themselves
and no third party gets to see the messages. Credentials are AES-256-GCM
encrypted in settings like every other secret, never in the repo. nodemailer
has zero dependencies and no native postinstall -- checked before adding it,
given the history.

Password reset: single-use token, only its hash is stored, one hour, and the
request endpoint answers identically whether or not the address exists so it
cannot be used to enumerate accounts. Rate limited per address.

Share links (/s/<slug>) let someone without an account see the pictures and
download them at full resolution. These are photos of children, so the
defaults lean safe: every link expires by itself (30 days), can be revoked,
optionally carries a passphrase, and the page and files are noindex. Access is
bound to the link, not the image -- swapping in another item id on a valid link
returns 404. Private-session results can never be shared at all.

Tracking records when and with what, never who: IP addresses are only stored
salted-and-hashed, so repeat visitors can be counted but nobody identified.

Sharing goes out by mail (several recipients at once, no attachment -- a link
can be withdrawn later, an attachment cannot) or via wa.me, which opens
WhatsApp with the text prepared. The WhatsApp Business API would need a Meta
account, approved templates and per-conversation fees; this works today for
free and the API can slot in behind it later.

Verified end to end against a local SMTP server: reset issues and consumes its
token exactly once, the old password stops working, an unknown address gives
the same answer, share mail reaches several recipients. Link behaviour checked
for expiry (410), revocation (410), wrong passphrase (401) and download lock
(403). Outbound SMTP is blocked in the sandbox, so the real mailbox still needs
one test from the live server.

Also fixes a regression this introduced: the seventh nav item pushed the logout
button off screen at 820px. The bar now shrinks and scrolls, logout never does.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BNhLunz586g6DeYMa7Qsd1

src/pages/api/admin/test-mail.ts

@@ -0,0 +1,34 @@
+import type { APIRoute } from 'astro';
+import { testMail, sendMail, mailLayout, istMail } from '../../../lib/mail';
+
+export const prerender = false;
+const json = (b: unknown, s = 200) =>
+  new Response(JSON.stringify(b), { status: s, headers: { 'Content-Type': 'application/json' } });
+
+/**
+ * Ohne `to`: nur die Verbindung prüfen (verschickt nichts).
+ * Mit `to`: eine echte Testnachricht schicken — erst das beweist, dass die
+ * Mail auch ankommt und nicht im Spam landet.
+ */
+export const POST: APIRoute = async ({ request }) => {
+  const b = await request.json().catch(() => ({}));
+  const to = String(b.to || '').trim();
+  if (!to) return json(await testMail());
+  if (!istMail(to)) return json({ ok: false, message: 'Das ist keine gültige Adresse.' }, 400);
+  try {
+    await sendMail({
+      to,
+      subject: 'Klarbild — Testnachricht',
+      text: 'Wenn du das liest, funktioniert der E-Mail-Versand aus Klarbild.\n\n'
+        + 'Damit können jetzt: Passwort-Rücksetzungen, Hinweise zu fertigen Aufträgen und Teilen-Links per Mail.',
+      html: mailLayout('Der Versand funktioniert', [
+        'Wenn du das liest, kommen E-Mails aus deiner Klarbild-Installation an.',
+        'Damit funktionieren jetzt: Passwort zurücksetzen, Hinweise zu fertigen Aufträgen und Teilen-Links per Mail.',
+      ]),
+    });
+    return json({ ok: true, message: `Testnachricht an ${to} verschickt. Schau auch im Spam-Ordner nach.` });
+  } catch (e: any) {
+    console.error('[test-mail]', e?.message || e);
+    return json({ ok: false, message: 'Versand fehlgeschlagen — Zugangsdaten und Port prüfen.' });
+  }
+};