feat: name output folder after the input .app file

Output directory is now derived from the input .app path (without
extension) instead of the intermediate VHD filename.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/main.rs

@@ -393,7 +393,8 @@ fn main() -> Result<()> {
             if deltas.is_empty() {
                 // Standalone base VHD, just extract
                 if let Some(base) = base {
-                    if let Err(e) = vhd::extract_vhd(&base.vhd_path) {
+                    let output_dir = base.input_path.with_extension("");
+                    if let Err(e) = vhd::extract_vhd(&base.vhd_path, &output_dir) {
                         println!("WARNING: VHD extraction failed: {e:#}");
                     }
                 }
@@ -408,7 +409,8 @@ fn main() -> Result<()> {
 
             // Merge + extract each delta with the base (pure Rust, no admin needed)
             for delta in &deltas {
-                if let Err(e) = vhd::extract_merged_vhd(&base.vhd_path, &delta.vhd_path) {
+                let output_dir = delta.input_path.with_extension("");
+                if let Err(e) = vhd::extract_merged_vhd(&base.vhd_path, &delta.vhd_path, &output_dir) {
                     println!("WARNING: Merged VHD extraction failed: {e:#}");
                 }
             }

src/vhd.rs

@@ -656,13 +656,13 @@ fn extract_ntfs_to_dir<T: Read + Seek>(fs: &mut T, output_dir: &Path, prefix: &s
 // ---------------------------------------------------------------------------
 
 /// Extract all files from a single VHD's NTFS filesystem, then delete the VHD.
-pub fn extract_vhd(vhd_path: &Path) -> Result<()> {
-    let output_dir = vhd_path.with_extension("");
+/// The `output_dir` is where files are extracted to.
+pub fn extract_vhd(vhd_path: &Path, output_dir: &Path) -> Result<()> {
     println!("Extracting VHD: {}", vhd_path.display());
 
     let mut vhd = VhdReader::new(File::open(vhd_path)?).map_err(|e| anyhow!(e))?;
-    let prefix = vhd_path.file_name().unwrap_or_default().to_string_lossy().to_string();
-    extract_ntfs_to_dir(&mut vhd, &output_dir, &prefix)?;
+    let prefix = output_dir.file_name().unwrap_or_default().to_string_lossy().to_string();
+    extract_ntfs_to_dir(&mut vhd, output_dir, &prefix)?;
 
     println!("Extracted to: {}", output_dir.display());
 
@@ -675,16 +675,16 @@ pub fn extract_vhd(vhd_path: &Path) -> Result<()> {
 
 /// Extract files from a merged view of base + delta VHDs (pure Rust, no admin needed).
 /// Reads delta blocks where available, falls back to base. Deletes both VHDs after.
-pub fn extract_merged_vhd(base_path: &Path, delta_path: &Path) -> Result<()> {
-    let output_dir = base_path.with_extension("");
+/// The `output_dir` is where files are extracted to.
+pub fn extract_merged_vhd(base_path: &Path, delta_path: &Path, output_dir: &Path) -> Result<()> {
     println!("Extracting merged VHD: {} + {}", base_path.display(), delta_path.display());
 
     let base = File::open(base_path)?;
     let delta = File::open(delta_path)?;
     let mut merged = MergedVhdReader::new(base, delta).map_err(|e| anyhow!(e))?;
 
-    let prefix = base_path.file_name().unwrap_or_default().to_string_lossy().to_string();
-    extract_ntfs_to_dir(&mut merged, &output_dir, &prefix)?;
+    let prefix = output_dir.file_name().unwrap_or_default().to_string_lossy().to_string();
+    extract_ntfs_to_dir(&mut merged, output_dir, &prefix)?;
 
     println!("Extracted to: {}", output_dir.display());