Give Bluetooth its factory address from the DPP partition

The WCN3990 has no burned-in Bluetooth address, so the kernel registers
the controller unconfigured and bluetoothd never sees it. The factory
address is on the machine all along: QCOM/BT.PROVISION on the DPP
partition, a three-byte header followed by the six-byte address.
c630-bt-addr reads it and hands it to btmgmt before bluetooth.service
starts. Verified on hardware: controller configures, powers, scans, and
streams A2DP.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011XgGF5wfxLDAybVnNz6eNQ

overlay/etc/systemd/system/c630-bt-addr.service

@@ -0,0 +1,15 @@
+[Unit]
+Description=Set the C630 Bluetooth factory address from the DPP partition
+# The WCN3990 has no burned-in address; the controller stays unconfigured and
+# invisible to bluetoothd until one is set. See /usr/local/sbin/c630-bt-addr.
+Before=bluetooth.service
+ConditionPathExists=/dev/disk/by-partlabel/DPP
+
+[Service]
+Type=oneshot
+ExecStart=/usr/local/sbin/c630-bt-addr
+RemainAfterExit=yes
+StandardOutput=journal
+
+[Install]
+WantedBy=multi-user.target