Function resolve_file_path 

pub fn resolve_file_path(user_path: &str, working_dir: &Path) -> PathBuf

Resolve a user-provided file path against the working directory.

Handles common LLM mistakes:

• ./src/main.rs -> strips ./ prefix
• ~/file.rs / $HOME/file.rs -> expands home directory
• myproject/main.rs when cwd is /home/user/myproject -> /home/user/myproject/main.rs (detects and strips redundant basename prefix)
• Absolute paths with doubled project name
• /workspace/foo or /testbed/foo -> {working_dir}/foo (LLM hallucination from Docker)