* Fix DNS migration to handle UseDNS=no in network files
Issue #1246: Migration 1755109182.sh only fixes resolved.conf but doesn't
remove UseDNS=no from network files. When UseDNS=no persists, it blocks
DHCP DNS and forces fallback to Cloudflare after reboot.
Fix: Remove UseDNS=no from all network files, matching omarchy-setup-dns DHCP behavior.
* Add new migration 1756491748.sh for existing users
Fixes DNS issue for users who already ran migration 1755109182.sh.
Removes UseDNS=no from network files to enable DHCP DNS.
* Apply requested changes
- Revert 1755109182.sh to original state
- Consolidate all fixes in new migration 1756491748.sh
- Follow migration style guidelines
