Major cleanup and optimization: Remove unused dependencies, clean build artifacts, and improve project structure

- Remove 7 unused dependencies: apt-pkg-native, pkg-config, walkdir, lazy_static, futures, async-trait, cap-std
- Delete dead code: Remove unused parallel.rs module
- Clean build artifacts: Remove debian/cargo/, debian/.debhelper/, and other build files
- Update .gitignore: Comprehensive patterns for build artifacts, test files, and temporary files
- Move documentation: Relocate project docs to docs/ directory
- Remove test artifacts: Clean up test files and package archives
- Update Cargo.toml: Streamline dependencies and remove unused features
- Verify build: Ensure project still compiles after cleanup

This commit significantly reduces project size and improves build efficiency.

Cargo.toml

@@ -9,15 +9,13 @@ keywords = ["apt", "ostree", "debian", "ubuntu", "package-management"]
 categories = ["system", "command-line-utilities"]
 
 [dependencies]
-# APT integration - using apt-pkg-native for better Debian Trixie compatibility
-apt-pkg-native = "0.3.3"
+# APT integration - using command-line tools (apt, apt-get, apt-cache, dpkg) for reliability and simplicity
 
 # OSTree integration
 ostree = "0.20.3"
 
 # System and FFI
 libc = "0.2"
-pkg-config = "0.3"
 num_cpus = "1.16"
 
 # Error handling
@@ -41,9 +39,6 @@ tracing-appender = "0.2"
 # Async runtime (used for concurrent operations)
 tokio = { version = "1.0", features = ["full"] }
 
-# File system operations
-walkdir = "2.4"
-
 # D-Bus integration (used for daemon communication)
 zbus = "4.0"
 zbus_macros = "4.0"
@@ -57,9 +52,6 @@ tar = "0.4"
 # Regular expressions
 regex = "1.0"
 
-# Lazy static initialization
-lazy_static = "1.4"
-
 # UUID generation
 uuid = { version = "1.0", features = ["v4"] }
 
@@ -73,18 +65,9 @@ polkit = "0.19"
 sha2 = "0.10"
 sha256 = "1.0"
 
-# Futures for async utilities
-futures = "0.3"
-async-trait = "0.1"
-
 # Development commands dependencies
 goblin = { version = "0.8", optional = true }           # ELF file manipulation
 rand = { version = "0.8", optional = true }             # Random number generation
-cap-std = { version = "1.0", optional = true }          # Capability-based file operations
-cap-std-ext = { version = "1.0", optional = true }      # Extended capability operations
-
-[build-dependencies]
-pkg-config = "0.3"
 
 [profile.release]
 opt-level = 3
@@ -97,8 +80,7 @@ debug = true
 
 [features]
 default = []
-development = ["goblin", "rand", "cap-std", "cap-std-ext"]
-dev-full = ["development", "cap-std", "cap-std-ext"]
+development = ["goblin", "rand"]
 
 [[bin]]
 name = "apt-ostree"