fix: remove container bluez, use host BlueZ via D-Bus, set DBUS_SYSTEM_BUS_ADDRESS

fichero_printer/Dockerfile

@@ -1,17 +1,17 @@
 ARG BUILD_FROM
 FROM $BUILD_FROM
 
-# Python 3, BlueZ and pre-compiled Alpine packages (no C compiler needed)
+# Only dbus-dev needed to talk to the HOST BlueZ via D-Bus (host_dbus: true).
+# Do NOT install bluez here - we use the host BlueZ, not our own.
 RUN apk add --no-cache \
     bash \
     python3 \
     py3-pip \
     py3-numpy \
     py3-pillow \
-    bluez \
-    dbus
+    dbus-dev
 
-# Pure-Python packages only (no compilation required)
+# Pure-Python packages (bleak uses dbus-fast internally, no C compiler needed)
 RUN pip3 install --no-cache-dir --break-system-packages \
     "bleak>=0.21" \
     "fastapi>=0.111" \