Add the ihasmail template for Unraid Community Applications

One XML per app under templates/, ca_profile.xml at the root, as the
Community Applications starter lays it out.

The ihasmail template runs the published multi-arch image read-only
with /tmp in memory, and as Unraid's nobody user (99:100) because that
is the owner Unraid gives a freshly created appdata folder; the image's
own user could not write the session file there. The appdata path is
optional: clear it, blank SESSION_FILE and set IMMUTABLE=1 for a
container with no writable path at all.

README.md

@@ -0,0 +1,56 @@
+# Coffey Labs Unraid templates
+
+Docker templates for [Unraid Community Applications](https://ca.unraid.net),
+one XML file per app under `templates/`. `ca_profile.xml` at the root is what
+Community Applications reads for the repository listing.
+
+| App | Template | Image | Licence of the app |
+| --- | --- | --- | --- |
+| [ihasmail](https://ihasmail.org) — immutable webmail for Stalwart Mail Server | [`templates/ihasmail.xml`](templates/ihasmail.xml) | `ghcr.io/coffey-labs/ihasmail:latest` (amd64, arm64) | AGPL-3.0-or-later |
+
+## Installing
+
+Once the repository is accepted into Community Applications, search for the
+app under **Apps** and install it from there.
+
+Until then, or if you prefer to skip the store, copy the template onto the
+flash drive from the Unraid terminal and it appears under **User templates**
+in the **Template** drop-down of **Docker → Add Container**:
+
+```sh
+wget -P /boot/config/plugins/dockerMan/templates-user/ \
+  https://raw.githubusercontent.com/Coffey-Labs/unraid-templates/main/templates/ihasmail.xml
+```
+
+## ihasmail
+
+ihasmail is a mail client, not a mail server. It needs a
+[Stalwart Mail Server](https://stalw.art) 0.16 or newer that the container can
+reach, and nothing else: no database, no appdata to migrate, no IMAP or SMTP
+settings. Everything durable lives in Stalwart.
+
+The template runs the container read-only, as Unraid's `nobody` user, with a
+`/tmp` in memory. The one optional write is `sessions.json` under
+`/mnt/user/appdata/ihasmail`, kept so nobody is signed out when the container
+restarts or updates. Clear that path, blank `SESSION_FILE` and set
+`IMMUTABLE=1` to run with no writable path at all, which is how
+[ihasmail.com](https://ihasmail.com) runs it.
+
+Two things to set on first install:
+
+- **Stalwart URL** — scheme and host, no path, e.g. `https://mail.example.com`.
+- **App secret** — a long random string. In the Unraid terminal:
+  `openssl rand -base64 48`.
+
+Put it behind a reverse proxy with HTTPS before exposing it beyond your LAN.
+Every other setting is documented at
+[docs.ihasmail.org/configure](https://docs.ihasmail.org/configure/).
+
+Problems with the app go to
+[Coffey-Labs/ihasmail issues](https://github.com/Coffey-Labs/ihasmail/issues);
+problems with the template go to the issues on this repository.
+
+## Licence
+
+The templates in this repository are MIT licensed. Each app keeps its own
+licence, shown in the table above.