fix(packaging): convert dispatch-systemd from user units to system template units (User=%i)

The per-user systemd manager ([email protected]) fails to start on WSL
(kernel 6.6.87.2, microsoft/WSL#13186 — 'Failed to spawn executor:
Device or resource busy'), which breaks pacman's
30-systemd-daemon-reload-user.hook on install.

Changes:
- New [email protected] + [email protected] system
  template units with User=%i (run as the named instance user)
- Remove old user-scope dispatch-api.service / dispatch-frontend.service
- Install to /usr/lib/systemd/system/ instead of .../systemd/user/
- Update PKGBUILD, .install hints, and bin/service to use
  sudo systemctl dispatch-api@<user>

7 files changed, 67 insertions, 50 deletions

diff --git a/packaging/PKGBUILD b/packaging/PKGBUILD
index a514eb5..6aa66cc 100644
--- a/packaging/PKGBUILD
+++ b/packaging/PKGBUILD
@@ -2,7 +2,7 @@
 #
 # Split package: builds the base application once and produces three packages:
 #   dispatch           — application files + CLI wrappers + env configs
-#   dispatch-systemd   — systemd user units for dispatch-api / dispatch-frontend
+#   dispatch-systemd   — systemd system units (run as a given user: dispatch-api@<user>)
 #   dispatch-s6        — s6 service definitions for dispatch-api / dispatch-frontend
 #
 # The Electron desktop wrapper lives in a separate PKGBUILD at packaging/electron/.
@@ -129,21 +129,25 @@ package_dispatch() {
 }
 
 # ----------------------------------------------------------------------------
-# dispatch-systemd — systemd user unit files
+# dispatch-systemd — systemd system unit templates (run as a chosen user)
+#
+# These are *system* units (managed by PID 1), not user units, so they do not
+# depend on a per-user `[email protected]` manager. Each is a template keyed on
+# the username: `dispatch-api@tradam` runs as the `tradam` user via User=%i.
 # ----------------------------------------------------------------------------
 package_dispatch-systemd() {
-	pkgdesc='Systemd user units for the Dispatch API and Frontend services'
+	pkgdesc='Systemd system unit templates for the Dispatch API and Frontend services (run as dispatch-api@<user>)'
 	depends=("dispatch=${pkgver}" 'systemd')
 	conflicts=('dispatch-s6')
 	install=dispatch-systemd.install
 
 	install -Dm644 \
-		"${_packagingdir}/dispatch-api.service" \
-		"${pkgdir}/usr/lib/systemd/user/dispatch-api.service"
+		"${_packagingdir}/[email protected]" \
+		"${pkgdir}/usr/lib/systemd/system/[email protected]"
 
 	install -Dm644 \
-		"${_packagingdir}/dispatch-frontend.service" \
-		"${pkgdir}/usr/lib/systemd/user/dispatch-frontend.service"
+		"${_packagingdir}/[email protected]" \
+		"${pkgdir}/usr/lib/systemd/system/[email protected]"
 }
 
 # ----------------------------------------------------------------------------
diff --git a/packaging/dispatch-api.service b/packaging/dispatch-api.service
deleted file mode 100644
index 120d460..0000000
--- a/packaging/dispatch-api.service
+++ /dev/null
@@ -1,15 +0,0 @@
-[Unit]
-Description=Dispatch API Backend
-
-[Service]
-Type=simple
-WorkingDirectory=/opt/dispatch
-ExecStart=/usr/bin/bun packages/api/src/index.ts
-EnvironmentFile=-/etc/dispatch/dispatch-api.conf
-Restart=on-failure
-RestartSec=5
-StandardOutput=journal
-StandardError=journal
-
-[Install]
-WantedBy=default.target
diff --git a/packaging/[email protected] b/packaging/[email protected]
new file mode 100644
index 0000000..3449fcb
--- /dev/null
+++ b/packaging/[email protected]
@@ -0,0 +1,21 @@
+# Dispatch API — system service template.
+# Runs under the system manager (PID 1) but drops privileges to the user named
+# in the instance: `dispatch-api@tradam` runs as the `tradam` user.
+#
+# Enable/start:
+#   sudo systemctl enable --now dispatch-api@<user>
+[Unit]
+Description=Dispatch API Backend (running as %i)
+After=network.target
+
+[Service]
+Type=simple
+User=%i
+WorkingDirectory=/opt/dispatch
+ExecStart=/usr/bin/bun packages/api/src/index.ts
+EnvironmentFile=-/etc/dispatch/dispatch-api.conf
+Restart=on-failure
+RestartSec=5
+
+[Install]
+WantedBy=multi-user.target
diff --git a/packaging/dispatch-frontend.service b/packaging/dispatch-frontend.service
deleted file mode 100644
index 4aca1a3..0000000
--- a/packaging/dispatch-frontend.service
+++ /dev/null
@@ -1,16 +0,0 @@
-[Unit]
-Description=Dispatch Frontend (static file server)
-After=dispatch-api.service
-
-[Service]
-Type=simple
-WorkingDirectory=/opt/dispatch
-ExecStart=/usr/bin/bun packages/frontend/serve.ts
-EnvironmentFile=-/etc/dispatch/dispatch-frontend.conf
-Restart=on-failure
-RestartSec=5
-StandardOutput=journal
-StandardError=journal
-
-[Install]
-WantedBy=default.target
diff --git a/packaging/[email protected] b/packaging/[email protected]
new file mode 100644
index 0000000..6f35cc1
--- /dev/null
+++ b/packaging/[email protected]
@@ -0,0 +1,22 @@
+# Dispatch Frontend — system service template.
+# Runs under the system manager (PID 1) but drops privileges to the user named
+# in the instance: `dispatch-frontend@tradam` runs as the `tradam` user.
+# Tied to the matching API instance for the same user.
+#
+# Enable/start:
+#   sudo systemctl enable --now dispatch-frontend@<user>
+[Unit]
+Description=Dispatch Frontend (static file server, running as %i)
+After=dispatch-api@%i.service
+
+[Service]
+Type=simple
+User=%i
+WorkingDirectory=/opt/dispatch
+ExecStart=/usr/bin/bun packages/frontend/serve.ts
+EnvironmentFile=-/etc/dispatch/dispatch-frontend.conf
+Restart=on-failure
+RestartSec=5
+
+[Install]
+WantedBy=multi-user.target
diff --git a/packaging/dispatch-systemd.install b/packaging/dispatch-systemd.install
index 3bd29be..5ebf261 100644
--- a/packaging/dispatch-systemd.install
+++ b/packaging/dispatch-systemd.install
@@ -1,24 +1,25 @@
 post_install() {
 	echo ""
-	echo "==> Dispatch systemd user units installed."
-	echo "    Enable and start:"
-	echo "      systemctl --user daemon-reload"
-	echo "      systemctl --user enable --now dispatch-api dispatch-frontend"
+	echo "==> Dispatch systemd system unit templates installed."
+	echo "    These run as the user named in the instance (replace <user>)."
+	echo "    Enable and start (e.g. for user 'tradam'):"
+	echo "      sudo systemctl daemon-reload"
+	echo "      sudo systemctl enable --now dispatch-api@<user> dispatch-frontend@<user>"
 	echo ""
 }
 
 post_upgrade() {
 	echo ""
 	echo "==> Dispatch systemd units upgraded."
-	echo "    Reload and restart:"
-	echo "      systemctl --user daemon-reload"
-	echo "      systemctl --user restart dispatch-api dispatch-frontend"
+	echo "    Reload and restart your instances (replace <user>):"
+	echo "      sudo systemctl daemon-reload"
+	echo "      sudo systemctl restart dispatch-api@<user> dispatch-frontend@<user>"
 	echo ""
 }
 
 pre_remove() {
 	echo ""
-	echo "==> Stop dispatch services before removal:"
-	echo "      systemctl --user disable --now dispatch-api dispatch-frontend"
+	echo "==> Stop dispatch services before removal (replace <user>):"
+	echo "      sudo systemctl disable --now dispatch-api@<user> dispatch-frontend@<user>"
 	echo ""
 }
diff --git a/packaging/dispatch.install b/packaging/dispatch.install
index 76837f5..75b36cc 100644
--- a/packaging/dispatch.install
+++ b/packaging/dispatch.install
@@ -11,7 +11,7 @@ post_install() {
 	echo "      dispatch-frontend     # static frontend (port 18391 by default)"
 	echo ""
 	echo "    To run as a service, install one of:"
-	echo "      pacman -S dispatch-systemd   # systemd user services"
+	echo "      pacman -S dispatch-systemd   # systemd system services (run as your user)"
 	echo "      pacman -S dispatch-s6        # s6 services (Artix)"
 	echo ""
 	echo "    For the Electron desktop wrapper:"
@@ -22,8 +22,8 @@ post_install() {
 post_upgrade() {
 	echo ""
 	echo "==> Dispatch (base) upgraded."
-	echo "    If you use dispatch-systemd, restart the units:"
-	echo "      systemctl --user restart dispatch-api dispatch-frontend"
+	echo "    If you use dispatch-systemd, restart the units (replace <user>):"
+	echo "      sudo systemctl restart dispatch-api@<user> dispatch-frontend@<user>"
 	echo "    If you use dispatch-s6, restart the services:"
 	echo "      s6-svc -r /run/service/dispatch-api"
 	echo "      s6-svc -r /run/service/dispatch-frontend"