Stage 9: CI build on a self-hosted Gitea runner (0.7.0)

- .gitea/workflows/build.yml builds the packages and both ISOs with
  `make iso iso-server` on pushes to main and dev, v* tags and on demand
- ci/runner: setup of the CI host (WSL2 Ubuntu 24.04 with Docker Engine
  and gitea-runner as a systemd service, autostart task for Windows)
- scripts/builder.sh: DASOS_OUT keeps out/ outside the checkout, so CI
  reuses void-packages, the masterdir and the download cache
- README and TODO updated

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ci/runner/autostart.ps1

@@ -0,0 +1,12 @@
+# Starts the dasci WSL distro (Docker and gitea-runner inside) when Windows
+# boots, without anyone logging in. Run once in an elevated PowerShell.
+# The task keeps a process attached so WSL never stops the distro as idle.
+$wsl = 'C:\Program Files\WSL\wsl.exe'
+$action = New-ScheduledTaskAction -Execute $wsl -Argument '-d dasci --exec /bin/sleep infinity'
+$trigger = New-ScheduledTaskTrigger -AtStartup
+$principal = New-ScheduledTaskPrincipal -UserId $env:USERNAME -LogonType S4U -RunLevel Highest
+$settings = New-ScheduledTaskSettingsSet -ExecutionTimeLimit 0 -AllowStartIfOnBatteries `
+  -DontStopIfGoingOnBatteries -RestartCount 999 -RestartInterval (New-TimeSpan -Minutes 1)
+Register-ScheduledTask -TaskName 'DasOS CI (WSL dasci)' -Action $action -Trigger $trigger `
+  -Principal $principal -Settings $settings -Force | Out-Null
+Get-ScheduledTask -TaskName 'DasOS CI (WSL dasci)' | Select-Object TaskName, State