fix(install): add CLI option validation, download-only wiring, and apcu-prefix implicit enable

- Restrict --prefer-install to source/dist/auto and --audit-format to
  table/plain/json/summary via clap value_parser
- Error when --prefer-install is combined with --prefer-source/--prefer-dist
- Wire --download-only through InstallConfig to skip autoloader and installed.json
- Implicitly enable --apcu-autoloader when --apcu-autoloader-prefix is set
- Apply same validation fixes to update, require, remove, create-project commands

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/crates/mozart/src/commands/update.rs b/crates/mozart/src/commands/update.rs
index 8bd694b..f33f1b0 100644
--- a/crates/mozart/src/commands/update.rs
+++ b/crates/mozart/src/commands/update.rs
@@ -24,7 +24,7 @@ pub struct UpdateArgs {
     pub prefer_dist: bool,
 
     /// Forces usage of a specific install method (dist, source, auto)
-    #[arg(long)]
+    #[arg(long, value_parser = ["source", "dist", "auto"])]
     pub prefer_install: Option<String>,
 
     /// Only output what would be changed, do not modify files
@@ -52,7 +52,7 @@ pub struct UpdateArgs {
     pub no_audit: bool,
 
     /// Audit output format
-    #[arg(long)]
+    #[arg(long, value_parser = ["table", "plain", "json", "summary"])]
     pub audit_format: Option<String>,
 
     /// Do not block on security advisories
@@ -1142,6 +1142,7 @@ pub async fn execute(
                 classmap_authoritative: args.classmap_authoritative,
                 apcu_autoloader: false,
                 apcu_autoloader_prefix: None,
+                download_only: false,
             },
         )
         .await?;