feat: Implement complete Zero OS Alpine Initramfs Builder

- Complete bash framework with strict error handling
- Modular library system (docker, alpine, components, initramfs, kernel, testing)
- Rust component integration (zinit, rfs, mycelium) with musl targeting
- Rootless Docker/Podman support for GitHub Actions
- Centralized configuration in config/build.conf
- 2-stage module loading system
- Strip + UPX optimization for minimal size
- Complete zinit integration replacing OpenRC
- GitHub Actions CI/CD pipeline
- Comprehensive documentation and usage guides

Components:
- Latest stable kernel 6.12.44
- Alpine Linux 3.22 base
- ThreeFold components: zinit, mycelium, rfs, corex
- Target: ~8-12MB final initramfs.cpio.xz

config/zinit/init/sshd-setup.sh

@@ -0,0 +1,15 @@
+#!/bin/ash
+if [ -f /etc/ssh/ssh_host_rsa_key ]; then
+    # ensure existing file permissions
+    chown root:root /etc/ssh/ssh_host_*
+    chmod 600 /etc/ssh/ssh_host_*
+    exit 0
+fi
+
+echo "Setting up sshd"
+mkdir -p /run/sshd
+
+ssh-keygen -f /etc/ssh/ssh_host_rsa_key -N '' -t rsa
+ssh-keygen -f /etc/ssh/ssh_host_dsa_key -N '' -t dsa
+ssh-keygen -f /etc/ssh/ssh_host_ecdsa_key -N '' -t ecdsa -b 521
+ssh-keygen -f /etc/ssh/ssh_host_ed25519_key -N '' -t ed25519