Added foundational modules for core functionalities:

- Introduced `walk.rs` as a parallel directory walker for search operations.
- Implemented basic index handling in `commands/index.rs`.
- Created `utils/config.rs` for configuration management with placeholders for future enhancements.

src/cli.rs

@@ -0,0 +1,88 @@
+use clap::{Parser, Subcommand};
+
+#[derive(Parser)]
+#[command(name = "nano")]
+#[command(about = "A fast vulnerability scanner with project indexing")]
+#[command(version)]
+pub struct Cli {
+    #[command(subcommand)]
+    pub(crate) command: Commands,
+}
+
+#[derive(Subcommand)]
+pub enum Commands {
+    /// Scan project for vulnerabilities
+    Scan {
+        /// Path to scan (defaults to current directory)
+        #[arg(default_value = ".")]
+        path: String,
+
+        /// Skip using/building index, scan directly
+        #[arg(long)]
+        no_index: bool,
+
+        /// Force rebuild index before scanning
+        #[arg(long)]
+        rebuild_index: bool,
+
+        /// Output format
+        #[arg(short, long, value_enum, default_value = "table")]
+        format: OutputFormat,
+
+        /// Show only high severity issues
+        #[arg(long)]
+        high_only: bool,
+    },
+
+    /// Manage project indexes
+    Index {
+        #[command(subcommand)]
+        action: IndexAction,
+    },
+
+    /// List all indexed projects
+    List {
+        /// Show detailed information
+        #[arg(short, long)]
+        verbose: bool,
+    },
+
+    /// Remove project from index
+    Clean {
+        /// Project name or path to clean
+        project: Option<String>,
+
+        /// Clean all projects
+        #[arg(long)]
+        all: bool,
+    },
+}
+
+#[derive(Subcommand)]
+pub enum IndexAction {
+    /// Build or update index for current project
+    Build {
+        /// Path to index (defaults to current directory)
+        #[arg(default_value = ".")]
+        path: String,
+
+        /// Force full rebuild
+        #[arg(short, long)]
+        force: bool,
+    },
+
+    /// Show index status and statistics
+    Status {
+        /// Project path to check
+        #[arg(default_value = ".")]
+        path: String,
+    },
+}
+
+#[derive(clap::ValueEnum, Clone, Debug)]
+pub enum OutputFormat {
+    Table,
+    Json,
+    Csv,
+    Sarif,
+}