fix(templated_uri): preserve error chain in remaining caused_by calls, simplify docs

- Use Into::into / ValidationError::from instead of caused_by in
  build_http_uri and Origin::from_str to preserve error sources
- Remove unnecessary Display impl from UriUnsafeParam derive example

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Kateřina Churanová

crates/templated_uri/src/base_uri.rs

@@ -600,7 +600,7 @@ impl BaseUri {
         parts.authority = Some(self.authority().clone());
         parts.path_and_query = Some(full_path);
 
-        http::Uri::from_parts(parts).map_err(ValidationError::caused_by)
+        http::Uri::from_parts(parts).map_err(Into::into)
     }
 }
 

crates/templated_uri/src/base_uri/origin.rs

@@ -131,7 +131,7 @@ impl std::str::FromStr for Origin {
     /// Returns a [`ValidationError`] if the string is not a valid origin
     /// (missing scheme, unsupported scheme, or invalid authority).
     fn from_str(s: &str) -> Result<Self, Self::Err> {
-        let uri: http::Uri = s.parse().map_err(ValidationError::caused_by)?;
+        let uri: http::Uri = s.parse().map_err(ValidationError::from)?;
         let scheme = uri.scheme().ok_or_else(|| ValidationError::caused_by("missing scheme"))?.clone();
         let authority = uri
             .authority()

crates/templated_uri/src/macros.rs

@@ -36,17 +36,10 @@ pub use templated_uri_macros::UriParam;
 /// # Example
 ///
 /// ```
-/// # use std::fmt::Display;
 /// use templated_uri::UriUnsafeParam;
 ///
 /// #[derive(UriUnsafeParam)]
 /// struct PathSegment(String);
-///
-/// impl Display for PathSegment {
-///     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-///         write!(f, "{}", self.0)
-///     }
-/// }
 /// ```
 ///
 /// This allows `PathSegment` to be used in URI templates with `{+param}` syntax where