refactor(installer): simplify code after review

- Remove dirs_home() and dead fallback in resolve_install_dir(), use
  get_vp_home() directly
- Resolve install dir once in run() and pass through to all functions
- Extract read_current_version() into vite_setup as a public function,
  reuse in save_previous_version() and the installer
- Merge Cli/Options structs into single Options struct in cli.rs
- Extract replace_windows_exe() helper to eliminate copy-paste in
  setup_bin_shims()
- Remove unused LPWSTR type alias from windows_path.rs
- Remove excessive "Step N" comments
- Fix mixed path separator in interactive menu display

Author: fengmk2

crates/vite_installer/src/cli.rs

@@ -5,79 +5,65 @@ use clap::Parser;
 /// Vite+ Installer — standalone installer for the vp CLI.
 #[derive(Parser, Debug)]
 #[command(name = "vp-setup", about = "Install the Vite+ CLI")]
-struct Cli {
+pub struct Options {
     /// Accept defaults without prompting (for CI/unattended installs)
     #[arg(short = 'y', long = "yes")]
-    yes: bool,
+    pub yes: bool,
 
     /// Suppress all output except errors
     #[arg(short = 'q', long = "quiet")]
-    quiet: bool,
+    pub quiet: bool,
 
     /// Install a specific version (default: latest)
     #[arg(long = "version")]
-    version: Option<String>,
+    pub version: Option<String>,
 
     /// npm dist-tag to install (default: latest)
     #[arg(long = "tag", default_value = "latest")]
-    tag: String,
+    pub tag: String,
 
     /// Custom installation directory (default: ~/.vite-plus)
     #[arg(long = "install-dir")]
-    install_dir: Option<String>,
+    pub install_dir: Option<String>,
 
     /// Custom npm registry URL
     #[arg(long = "registry")]
-    registry: Option<String>,
+    pub registry: Option<String>,
 
     /// Skip Node.js version manager setup
     #[arg(long = "no-node-manager")]
-    no_node_manager: bool,
+    pub no_node_manager: bool,
 
     /// Do not modify the User PATH
     #[arg(long = "no-modify-path")]
-    no_modify_path: bool,
-}
-
-/// Parsed installation options.
-pub struct Options {
-    pub yes: bool,
-    pub quiet: bool,
-    pub version: Option<String>,
-    pub tag: String,
-    pub install_dir: Option<String>,
-    pub registry: Option<String>,
-    pub no_node_manager: bool,
     pub no_modify_path: bool,
 }
 
 /// Parse CLI arguments, merging with environment variables.
-///
 /// CLI flags take precedence over environment variables.
 pub fn parse() -> Options {
-    let cli = Cli::parse();
-
-    // Environment variable overrides (CLI flags take precedence)
-    let version = cli.version.or_else(|| std::env::var("VP_VERSION").ok());
-    let install_dir = cli.install_dir.or_else(|| std::env::var("VP_HOME").ok());
-    let registry = cli.registry.or_else(|| std::env::var("NPM_CONFIG_REGISTRY").ok());
+    let mut opts = Options::parse();
 
-    let no_node_manager = cli.no_node_manager
-        || std::env::var("VP_NODE_MANAGER")
+    // Merge env var overrides (CLI flags already set take precedence)
+    if opts.version.is_none() {
+        opts.version = std::env::var("VP_VERSION").ok();
+    }
+    if opts.install_dir.is_none() {
+        opts.install_dir = std::env::var("VP_HOME").ok();
+    }
+    if opts.registry.is_none() {
+        opts.registry = std::env::var("NPM_CONFIG_REGISTRY").ok();
+    }
+    if !opts.no_node_manager {
+        opts.no_node_manager = std::env::var("VP_NODE_MANAGER")
             .ok()
             .is_some_and(|v| v.eq_ignore_ascii_case("no"));
+    }
 
     // quiet implies yes
-    let yes = cli.yes || cli.quiet;
-
-    Options {
-        yes,
-        quiet: cli.quiet,
-        version,
-        tag: cli.tag,
-        install_dir,
-        registry,
-        no_node_manager,
-        no_modify_path: cli.no_modify_path,
+    if opts.quiet {
+        opts.yes = true;
     }
+
+    opts
 }