fix: remove serial console (root cause of 30s boot delay), enable syslog logging, disk auto-detect

Root cause found: console=ttyS0,115200n8 causes 30-second timeout at every
systemd boot phase on hardware without a physical serial UART. Each phase
transition blocks waiting for the non-existent UART.

Changes:
- Remove console=ttyS0 from kickstart bootloader args and %post setup
- Enable Anaconda syslog forwarding (logging --host --port) for install visibility
- Improve syslog IP→MAC resolution (register from kickstart fetch + progress)
- Fix disk auto-detect: default to empty string (not /dev/sda) for NVMe support
- Enable SysRq magic keys (kernel.sysrq=1) for emergency reboot via JetKVM
- Simplify debug command: remove --sshd flag (inst.sshd always available),
  add /debug-setup.sh HTTP endpoint for nc listener setup
- Add labctl provision logs -f (follow mode with polling)
- Add syslog listener unit tests
- Enable syslog log capture test in integration suite

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

bastion/completions/labctl.fish

@@ -138,7 +138,10 @@ complete -c labctl -n "__labctl_in_cmd provision reprovision" -l os -d 'Operatin
 complete -c labctl -n "__labctl_in_cmd provision reprovision" -l disk -d 'Target disk device (auto-detect if omitted)' -x
 
 # provision debug options
-complete -c labctl -n "__labctl_in_cmd provision debug" -l sshd -d 'Start SSH + nc listener automatically, report IP to bastion'
+complete -c labctl -n "__labctl_in_cmd provision debug" -l pxe-boot -d 'Boot installed system via PXE (kernel+initrd from network, root from NVMe)'
+
+# provision logs options
+complete -c labctl -n "__labctl_in_cmd provision logs" -s f -l follow -d 'Follow log output in real-time'
 
 # provision makeiso options
 complete -c labctl -n "__labctl_in_cmd provision makeiso" -l arch -d 'Target architecture(s)' -xa 'x86_64 aarch64'