build: ship the systemd unit from the crate

cce-status-interface.service existed only as a hand-written file in
~/.config/systemd/user, tracked in no repo, so a fresh clone lost the status
bar's autostart and nothing here would recreate it — the same gap the .desktop
entries, cce-keyring-selftest and cce-remote.service each had.

ccebuild discovers units at a crate root and classifies them by their own
[Install] WantedBy; graphical-session.target is already a user target, so
shipping it needs no other change and it installs to the path the hand-written
copy occupied. Content is byte-identical to that copy — verified with diff
before the install, so this changes what is versioned, not what runs.

Co-Authored-By: Claude Opus 5 <[email protected]>

 cce-status-interface.service | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/cce-status-interface.service b/cce-status-interface.service
new file mode 100644
index 0000000..dfc549c
--- /dev/null
+++ b/cce-status-interface.service
@@ -0,0 +1,14 @@
+[Unit]
+Description=CCE Status Interface (Wayland Bar)
+After=graphical-session.target
+PartOf=graphical-session.target
+
+[Service]
+Type=simple
+ExecStart=%h/.local/bin/cce-status-interface
+Restart=on-failure
+RestartSec=3
+Environment=RUST_LOG=info
+
+[Install]
+WantedBy=graphical-session.target