Implement SparkOS MVP: init system, build infrastructure, and rootfs

Co-authored-by: johndoe6345789 <224850594+johndoe6345789@users.noreply.github.com>

ARCHITECTURE.md

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+# SparkOS Architecture
+
+## Overview
+
+SparkOS is designed as a minimal Linux distribution with a custom init system and a modular architecture that allows for future expansion.
+
+## System Components
+
+### 1. Init System (`/sbin/init`)
+
+The init system is the first process started by the kernel (PID 1). It is responsible for:
+
+- **Mounting filesystems**: proc, sys, dev, tmp
+- **Process management**: Spawning and respawning the shell
+- **Signal handling**: Reaping zombie processes
+- **System initialization**: Setting up the initial environment
+
+**Implementation**: `src/init.c`
+- Written in C for minimal overhead
+- Statically linked for independence
+- ~100 lines of clean, well-documented code
+
+### 2. Root Filesystem
+
+Follows the Filesystem Hierarchy Standard (FHS):
+
+```
+/
+├── bin/          Essential user binaries (bash, ls, cp, etc.)
+├── sbin/         System binaries (init, mount, etc.)
+├── etc/          System configuration files
+├── proc/         Kernel process information (virtual)
+├── sys/          Kernel system information (virtual)
+├── dev/          Device files (virtual)
+├── tmp/          Temporary files
+├── usr/
+│   ├── bin/      Non-essential user binaries
+│   ├── sbin/     Non-essential system binaries
+│   ├── lib/      Libraries for /usr/bin and /usr/sbin
+│   └── lib64/    64-bit libraries
+├── var/          Variable data (logs, caches)
+├── root/         Root user home directory
+└── home/         User home directories
+```
+
+### 3. Build System
+
+**Makefile**: Main build orchestration
+- `make init`: Compile init system
+- `make install`: Install init to rootfs
+- `make image`: Create bootable image (requires root)
+- `make clean`: Clean build artifacts
+
+**Scripts**:
+- `scripts/build.sh`: Quick build for development
+- `scripts/setup_rootfs.sh`: Create rootfs structure
+- `scripts/create_image.sh`: Create dd-able disk image
+
+### 4. Boot Process
+
+```
+Hardware Power-On
+    ↓
+BIOS/UEFI
+    ↓
+Bootloader (syslinux)
+    ↓
+Linux Kernel (vmlinuz)
+    ↓
+Init System (/sbin/init) [PID 1]
+    ↓
+Mount filesystems
+    ↓
+Spawn bash shell
+    ↓
+User interaction
+```
+
+## Design Decisions
+
+### Why Custom Init?
+
+- **Simplicity**: No dependencies, easy to understand
+- **Control**: Full control over boot process
+- **Size**: Minimal footprint (<1MB statically linked)
+- **Learning**: Educational value for OS development
+
+### Why Static Linking?
+
+- **Independence**: No library dependencies
+- **Portability**: Works on any Linux system
+- **Reliability**: No missing library issues
+
+### Why Bash?
+
+- **Familiar**: Most users know bash
+- **Powerful**: Full scripting capabilities
+- **Standard**: Available on virtually all Linux systems
+
+## Future Architecture
+
+### Planned Components
+
+1. **Qt6/QML GUI**
+   - Full-screen Wayland application
+   - Android-like interface design
+   - Desktop-oriented workflow
+
+2. **Wayland Compositor**
+   - Custom compositor for SparkOS
+   - Minimal resource usage
+   - Touch and mouse support
+
+3. **C++ CLI Tools**
+   - System management utilities
+   - Package management
+   - Network configuration
+
+4. **Sudo Integration**
+   - Proper privilege elevation
+   - Security policies
+   - Audit logging
+
+## Security Considerations
+
+- Static binaries reduce attack surface
+- Minimal running processes
+- Root filesystem can be read-only
+- Future: sudo for privilege escalation
+- Future: SELinux/AppArmor integration
+
+## Performance
+
+- Fast boot time (seconds, not minutes)
+- Low memory footprint (~100MB base system)
+- No unnecessary background services
+- Efficient init system
+
+## Portability
+
+- AMD64 architecture (x86_64)
+- dd-able disk images
+- USB flash drive ready
+- Future: ARM64 support
+
+## Extension Points
+
+The architecture is designed for easy extension:
+
+1. **Init system**: Can be enhanced with service management
+2. **Filesystem**: Can add more mount points and partitions
+3. **Boot process**: Can integrate other bootloaders
+4. **GUI**: Clean separation allows GUI to be optional
+
+## Development Workflow
+
+1. Modify source code in `src/`
+2. Build with `make init`
+3. Test init in isolation
+4. Install to `rootfs/` with `make install`
+5. Create test image with `sudo make image`
+6. Test on real hardware or VM
+
+## References
+
+- Linux Kernel Documentation
+- Filesystem Hierarchy Standard (FHS)
+- POSIX Standards
+- Qt6 Documentation
+- Wayland Protocol Specification