release: 0.1.0: Phases 0-11: panel, Postfix/DKIM, milter, backup, Docker image

Initial feature-complete implementation of the v1.0 specification (phases 0-11 of `docs/implementation-plan.md`).
Added:
  - Panel (Go, single static binary) with SQLite persistence, one-time
  - Domain management with per-domain DKIM (RSA-2048, generated in pure Go) and
  - Application (sender identity) management: SASL credentials via `sasldb2`,
  - Full Postfix relay config generated from env at container start: SMTPS 465,
  - Journal milter (pure Go, `go-milter`) recording every send to `send_log`;
  … (6 more in CHANGELOG)

Full detail: CHANGELOG.md (0.1.0).

internal/web/templates/backup.html

@@ -0,0 +1,32 @@
+{{define "content"}}
+<h1>Backup &amp; migration</h1>
+
+<div class="card">
+  <h2>Full backup</h2>
+  <p class="muted">Download a full backup of all persistent state — the database,
+  every domain's DKIM key and the application credentials. Use it to move the
+  whole server to a new machine: restore it into a container of the
+  <strong>same SelfPost version</strong>, with the same data mount, before first
+  start. TLS certificates and the mail queue are not included.</p>
+  <p class="muted"><strong>The backup file is a secret</strong> (it contains
+  private keys and credentials). Store and transfer it securely and delete it
+  once the restore succeeds.</p>
+  <form class="inline" method="post" action="/backup">
+    <button type="submit">Download full backup</button>
+  </form>
+</div>
+
+<div class="card">
+  <h2>Import a domain</h2>
+  <p class="muted">Move a single domain here from another SelfPost instance using
+  a domain export file (from that domain's page). Its DKIM key and application
+  passwords come across, so the published DNS record needs no change. The export
+  file is a secret, like a full backup.</p>
+  {{if .ImportErr}}<p class="error">{{.ImportErr}}</p>{{end}}
+  <form method="post" action="/domains/import" enctype="multipart/form-data">
+    <label for="importfile">Domain export file</label>
+    <input id="importfile" name="file" type="file" accept=".json,application/json" required>
+    <button type="submit">Import domain</button>
+  </form>
+</div>
+{{end}}