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/apk/keys/alpine-devel@lists.alpinelinux.org-616ae350.rsa.pub

@@ -0,0 +1,14 @@
+-----BEGIN PUBLIC KEY-----
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+HwsGXBTVcfXg44RLyL8Lk/2dQxDHNHzAUslJXzPxaHBLmt++2COa2EI1iWlvtznk
+Ok9WP8SOAIj+xdqoiHcC4j72BOVVgiITIJNHrbppZCq6qPR+fgXmXa+sDcGh30m6
+9Wpbr28kLMSHiENCWTdsFij+NQTd5S47H7XTROHnalYDuF1RpS+DpQidT5tUimaT
+JZDr++FjKrnnijbyNF8b98UCAwEAAQ==
+-----END PUBLIC KEY-----