style: use short Error path in find_project_root, restore comment

Author: rocketman-code

src/build.rs

@@ -167,18 +167,18 @@ pub fn find_workspace_root(project_dir: &Path) -> Option<PathBuf> {
 ///
 /// Returns the canonicalized directory containing the nearest Cargo.toml.
 /// Starts checking `start_dir` itself, then walks up through parents.
-pub fn find_project_root(start_dir: &Path) -> Result<PathBuf, crate::error::Error> {
+pub fn find_project_root(start_dir: &Path) -> Result<PathBuf, Error> {
     let start = start_dir
         .canonicalize()
-        .map_err(|_| crate::error::Error::NoProjectFound(start_dir.to_path_buf()))?;
+        .map_err(|_| Error::NoProjectFound(start_dir.to_path_buf()))?;
     let mut dir = start.as_path();
     loop {
         if dir.join("Cargo.toml").exists() {
             return Ok(dir.to_path_buf());
         }
         match dir.parent() {
             Some(parent) => dir = parent,
-            None => return Err(crate::error::Error::NoProjectFound(start_dir.to_path_buf())),
+            None => return Err(Error::NoProjectFound(start_dir.to_path_buf())),
         }
     }
 }

src/main.rs

@@ -631,6 +631,7 @@ fn default_tags_dir() -> Result<PathBuf, Error> {
     if local.is_dir() {
         return Ok(local);
     }
+    // Auto-create tags dir if runs exist (tags live alongside runs)
     let runs_local = project.join("target/piano/runs");
     if runs_local.is_dir() {
         std::fs::create_dir_all(&local)?;