Add version flag to CLI and improve installer

- Added version support to the CLI using the clap derive macro.
- Updated the install script to verify the installation using the new
  version flag, with a fallback to help if the flag is unavailable.

Author: PythonicNinja

scripts/install.sh

@@ -156,7 +156,12 @@ fi
 install -m 0755 "${TMP_DIR}/trigrep" "${INSTALL_DIR}/trigrep"
 
 echo "==> Installed to ${INSTALL_DIR}/trigrep"
-"${INSTALL_DIR}/trigrep" --version
+if "${INSTALL_DIR}/trigrep" --version >/dev/null 2>&1; then
+  "${INSTALL_DIR}/trigrep" --version
+else
+  echo "==> Warning: installed binary does not support --version; use 'trigrep --help'" >&2
+  "${INSTALL_DIR}/trigrep" --help >/dev/null
+fi
 
 case ":$PATH:" in
   *":${INSTALL_DIR}:"*) ;;

trigrep-cli/src/main.rs

@@ -8,7 +8,11 @@ use std::path::PathBuf;
 use clap::{Parser, Subcommand};
 
 #[derive(Parser)]
-#[command(name = "trigrep", about = "Indexed regex search for large codebases")]
+#[command(
+    name = "trigrep",
+    about = "Indexed regex search for large codebases",
+    version
+)]
 struct Cli {
     #[command(subcommand)]
     command: Commands,