feat(src): Introduce full CLI interface for laptop hardware management

Add clap‑based CLI with subcommands (gpu, battery, power, status), verbose flag, and detailed options such as rtd3, use_nvidia_current, etc.
- New Features
  - New CLI entry point with complete subcommand hierarchy
  - Verbose logging support
  - Granular command options for GPU, Battery, Power, Status
- Enhancements
  - Replace placeholder hello world with proper logging initialization
  - Modularize command implementations into dedicated modules

src/cli.rs

@@ -0,0 +1,102 @@
+use clap::{Parser, Subcommand};
+
+#[derive(Parser, Debug)]
+#[command(
+    name = "lapctl",
+    version,
+    about = "CLI utility for managing laptop hardware features on Linux."
+)]
+pub struct Cli {
+    #[command(subcommand)]
+    pub command: Commands,
+
+    /// Enable verbose logging
+    #[arg(short, long, global = true)]
+    pub verbose: bool,
+}
+
+#[derive(Subcommand, Debug)]
+pub enum Commands {
+    /// GPU management commands
+    Gpu {
+        #[command(subcommand)]
+        command: GpuCommands,
+    },
+    /// Battery management commands
+    Battery {
+        #[command(subcommand)]
+        command: BatteryCommands,
+    },
+    /// Power management commands
+    Power {
+        #[command(subcommand)]
+        command: PowerCommands,
+    },
+    /// Hardware status
+    Status,
+}
+
+#[derive(Subcommand, Debug)]
+pub enum GpuCommands {
+    /// Query the current graphics mode
+    Query,
+    /// Switch to integrated graphics
+    Integrated,
+    /// Switch to hybrid graphics
+    Hybrid {
+        /// Setup PCI-Express Runtime D3 (RTD3) Power Management on Hybrid mode (0, 1, 2, 3)
+        #[arg(long)]
+        rtd3: Option<u8>,
+        /// Use nvidia-current instead of nvidia for kernel modules
+        #[arg(long)]
+        use_nvidia_current: bool,
+    },
+    /// Switch to NVIDIA graphics
+    Nvidia {
+        /// Manually specify your Display Manager (gdm, sddm, lightdm)
+        #[arg(long)]
+        dm: Option<String>,
+        /// Enable ForceCompositionPipeline on Nvidia mode
+        #[arg(long)]
+        force_comp: bool,
+        /// Enable Coolbits on Nvidia mode
+        #[arg(long)]
+        coolbits: Option<u32>,
+        /// Use nvidia-current instead of nvidia for kernel modules
+        #[arg(long)]
+        use_nvidia_current: bool,
+        /// Set up Nvidia mode for Wayland (skips Xorg configuration)
+        #[arg(long)]
+        wayland: bool,
+    },
+    /// Revert changes made by lapctl
+    Reset,
+    /// Restore default sddm Xsetup file
+    ResetSddm,
+    /// Create cache used by lapctl (hybrid mode only)
+    CacheCreate,
+    /// Delete cache created by lapctl
+    CacheDelete,
+    /// Show cache created by lapctl
+    CacheQuery,
+}
+
+#[derive(Subcommand, Debug)]
+pub enum PowerCommands {
+    /// Set power profile to performance
+    Performance,
+    /// Set power profile to balanced
+    Balanced,
+    /// Set power profile to battery saver
+    BatterySave,
+}
+
+#[derive(Subcommand, Debug)]
+pub enum BatteryCommands {
+    /// Set the battery charging limit (e.g., 80)
+    Limit {
+        percent: u8,
+    },
+    /// Show current battery status
+    Status,
+}