fix: Switch to space-separated sources.conf format

- Change from colon to space separation to avoid URL parsing issues
- Update sources.conf format: TYPE NAME URL VERSION BUILD_FUNCTION [EXTRA]
- Implement awk-based parsing for reliable field extraction
- Fix firmware package list (remove unavailable linux-firmware-marvell)

initramfs/usr/share/metainfo/org.kernel.software.network.ethtool.metainfo.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<component type="console-application">
+  <id>org.kernel.software.network.ethtool</id>
+  <metadata_license>MIT</metadata_license>
+  <name>ethtool</name>
+  <summary>display or change Ethernet device settings</summary>
+  <description>
+    <p>ethtool can be used to query and change settings such as speed,
+    auto- negotiation and checksum offload on many network devices,
+    especially Ethernet devices.</p>
+  </description>
+  <url type="homepage">https://www.kernel.org/pub/software/network/ethtool/</url>
+  <provides>
+    <binary>ethtool</binary>
+    <modalias>pci:v*d*sv*sd*bc02sc80i*</modalias>
+  </provides>
+</component>