feat(cli): implement register and unregister commands with scope support

- Add Target enum to handle user/system scope selection
- Move scope argument from global CLI to register/unregister subcommands
- Implement actual registration logic including ProgId subkey creation
- Update Program::new to accept string path instead of Path
- Add proper error handling and success messages

wfassoc_exec/src/cli.rs

@@ -1,10 +1,28 @@
-use clap::{Parser, Subcommand};
+use clap::{Parser, Subcommand, ValueEnum};
+use wfassoc::Scope;
+
+#[derive(Debug, Clone, ValueEnum)]
+pub enum Target {
+    #[value(name = "user")]
+    User,
+    #[value(name = "system")]
+    System,
+}
+
+impl From<Target> for Scope {
+    fn from(target: Target) -> Self {
+        match target {
+            Target::User => Scope::User,
+            Target::System => Scope::System,
+        }
+    }
+}
 
 /// Simple program to manage Windows file associations
 #[derive(Parser)]
 #[command(name = "Windows File Association Operator", version, about)]
 pub struct Cli {
-    /// The toml file introducing the complete program
+    /// The TOML file representing the complete program
     #[arg(
         short = 'c',
         long = "config",
@@ -13,40 +31,30 @@ pub struct Cli {
     )]
     pub(crate) config_file: String,
 
-    /// The scope where wfassoc operate
-    #[arg(short = 'f', long = "for", value_name = "TARGET", value_enum, default_value_t = ForTarget::User)]
-    pub(crate) for_which: ForTarget,
-
     #[command(subcommand)]
     pub(crate) command: Commands,
 }
 
-#[derive(clap::ValueEnum, Clone)]
-pub enum ForTarget {
-    #[value(name = "user")]
-    User,
-    #[value(name = "system")]
-    System,
-}
-
-// impl From<ForTarget> for RegisterKind {
-//     fn from(target: ForTarget) -> Self {
-//         match target {
-//             ForTarget::User => RegisterKind::User,
-//             ForTarget::System => RegisterKind::System,
-//         }
-//     }
-// }
-
 #[derive(Subcommand)]
 pub enum Commands {
     /// Register the program
     #[command(name = "register")]
-    Register,
+    #[command(about = "Register application with given manifest and scope.")]
+    Register {
+        /// The scope where wfassoc operate
+        #[arg(short = 't', long = "target", value_name = "TARGET", value_enum, default_value_t = Target::User)]
+        target: Target,
+    },
     /// Unregister the program
     #[command(name = "unregister")]
-    Unregister,
+    #[command(about = "Unregister application with given manifest and scope.")]
+    Unregister {
+        /// The scope where wfassoc operate
+        #[arg(short = 't', long = "target", value_name = "TARGET", value_enum, default_value_t = Target::User)]
+        target: Target,
+    },
     /// Query file associations
     #[command(name = "query")]
+    #[command(about = "Query file extensions association infos according toh given manifest represented application.")]
     Query,
 }