docs: Better systemd unit file for AI workers

The original method added complexity of a script file which requires
`chmod +x`, runs sudo on each invocation (which can spam logs), and
does not invoke `systemctl daemon-reload` before starting the units
leading to warnings (though not fatal).

This new flow uses systemd's own execution environment (including
handling the user) and simplifies the dependencies. Activation is also
streamlined since systemctl can handle multiple units in one command,
avoiding shell `for` loops.

Signed-off-by: Liam Dennehy <liam@wiemax.net>

Author: liamdennehy

admin_manual/ai/overview.rst

@@ -364,51 +364,55 @@ The logs of the worker can be checked by attaching to the screen or tmux session
 Systemd service
 ^^^^^^^^^^^^^^^
 
-1. Create a systemd service file in ``/etc/systemd/system/nextcloud-ai-worker@.service`` with the following content:
+This section assumes four workers are to be run simultaneously, the suggested default.
+
+1. Note the location of your php executable, and create a systemd service file for the AI workers:
+
+.. code-block:: console
+
+   $ which php
+   /usr/bin/php
+   $ sudo systemctl edit --full --force nextcloud-ai-worker@.service
+
+Paste the following content into the editor:
 
 .. code-block::
 
    [Unit]
    Description=Nextcloud AI worker %i
-   After=network.target
-
+   
    [Service]
-   ExecStart=/opt/nextcloud-ai-worker/taskprocessing.sh %i
+   WorkingDirectory=/path/to/nextcloud
+   User=www-data
+   ExecStart=/usr/bin/php occ taskprocessing:worker -v -t 60
    Restart=always
    StartLimitInterval=60
    StartLimitBurst=10
 
    [Install]
    WantedBy=multi-user.target
 
-2. Create a shell script in ``/opt/nextcloud-ai-worker/taskprocessing.sh`` with the following content and make sure to make it executable:
-
-.. code-block::
-
-   #!/bin/sh
-   echo "Starting Nextcloud AI Worker $1"
-   cd /path/to/nextcloud
-   sudo -E -u www-data php occ taskprocessing:worker -v -t 60
+Make sure the ``ExecStart=`` line above points to your php execuatable file location
 
-You may want to adjust the timeout to your needs (in seconds).
+You may want to adjust the timeout (``-t 60`` above) to your needs (in seconds).
 
-3. Enable and start the service 4 or more times:
+2. Enable and start 4 instances of the service (the command can be safely re-run with a higher value if more instances are needed):
 
 .. code-block::
 
-   for i in {1..4}; do systemctl enable --now nextcloud-ai-worker@$i.service; done
+   systemctl enable --now nextcloud-ai-worker@{1..4}.service
 
-The status of the workers can be checked with (replace 1 with the worker number):
+The status of the workers can be checked with:
 
 .. code-block::
 
-   systemctl status nextcloud-ai-worker@1.service
+   systemctl status nextcloud-ai-worker@{1..4}.service
 
 The list of workers can be checked with:
 
 .. code-block::
 
-   systemctl list-units --type=service | grep nextcloud-ai-worker
+   systemctl list-units --type=service | grep nextcloud-ai-worker@
 
 The complete logs of the workers can be checked with (replace 1 with the worker number):