refactor: improve error handling patterns and code quality

- replace map_err with inspect_err for side-effect error logging
- simplify conditional unwrapping using if-let patterns
- fix integer cast warning in status display calculation
- update build command documentation to include clippy

Author: eugener

CLAUDE.md

@@ -21,7 +21,7 @@
 - Utility functions: git(args, working_dir) -> Result<String>, git_raw(args, working_dir) -> Result<Output>
 - Command modules: status.rs, add.rs, commit.rs (in src/commands/)
 - Core types: Hash (in src/types.rs)
-- Run `cargo build && cargo test` after code changes
+- Run `cargo build && cargo test && cargo clippy --all-targets --all-features -- -D warnings` after code changes
 - Make sure all examples are running
 
 ## Examples

examples/error_handling.rs

@@ -31,7 +31,7 @@ fn main() -> Result<()> {
     demonstrate_file_operation_errors(&repo_path)?;
     demonstrate_git_command_errors(&repo_path)?;
     demonstrate_error_recovery_patterns(&repo_path)?;
-    demonstrate_error_propagation_strategies(&base_path)?;
+    demonstrate_error_propagation_strategies(base_path)?;
 
     // Clean up
     println!("Cleaning up error handling examples...");
@@ -405,9 +405,8 @@ fn workflow_with_context(base_path: &str) -> Result<String> {
 
     // Add context to errors
     let repo = Repository::init(&repo_path, false)
-        .map_err(|e| {
+        .inspect_err(|_e| {
             eprintln!("Context: Failed to initialize repository at {}", repo_path);
-            e
         })?;
 
     // Create file with context
@@ -419,16 +418,14 @@ fn workflow_with_context(base_path: &str) -> Result<String> {
 
     // Add with context
     repo.add(&["context_file.txt"])
-        .map_err(|e| {
+        .inspect_err(|_e| {
             eprintln!("Context: Failed to stage context_file.txt");
-            e
         })?;
 
     // Commit with context
     let hash = repo.commit("Context workflow commit")
-        .map_err(|e| {
+        .inspect_err(|_e| {
             eprintln!("Context: Failed to create commit");
-            e
         })?;
 
     // Clean up

examples/staging_operations.rs

@@ -259,7 +259,7 @@ fn display_status_changes(before: &rustic_git::GitStatus, after: &rustic_git::Gi
         let after_val = after_counts.get(status).unwrap_or(&0);
 
         if before_val != after_val {
-            println!("      {}: {} → {} ({:+})", status, before_val, after_val, *after_val as i32 - *before_val as i32);
+            println!("      {}: {} → {} ({:+})", status, before_val, after_val, *after_val - *before_val);
         }
     }
 }

src/repository.rs

@@ -292,8 +292,7 @@ mod tests {
 
         let result = Repository::init(test_path, false);
 
-        if result.is_ok() {
-            let repo = result.unwrap();
+        if let Ok(repo) = result {
             assert_eq!(repo.repo_path(), Path::new(test_path));
 
             // Clean up
@@ -335,8 +334,7 @@ mod tests {
 
         let result = Repository::init(test_path, false);
 
-        if result.is_ok() {
-            let repo = result.unwrap();
+        if let Ok(repo) = result {
             assert_eq!(repo.repo_path(), Path::new(test_path));
 
             // Clean up
@@ -355,8 +353,7 @@ mod tests {
 
         let result = Repository::init(test_path, false);
 
-        if result.is_ok() {
-            let repo = result.unwrap();
+        if let Ok(repo) = result {
             assert_eq!(repo.repo_path(), Path::new(test_path));
 
             // Clean up
@@ -376,8 +373,7 @@ mod tests {
 
         let result = Repository::init(&test_path, false);
 
-        if result.is_ok() {
-            let repo = result.unwrap();
+        if let Ok(repo) = result {
             assert_eq!(repo.repo_path(), Path::new(&test_path));
 
             // Clean up