refactor: unify error handling with anyhow and add From conversions

Phase 5: Replace all Box<dyn Error> return types with anyhow::Result<T>
throughout the codebase. Replace string-based Err("msg".into()) and
format!().into() patterns with bail!() and anyhow!() macros. Fix
dirs::home_dir().unwrap() in settings.rs to use a fallback path instead
of panicking when HOME is unset. Remove stray use std::error::Error
imports no longer needed.

Phase 6: Add From<&User> for CacheUser in models/user.rs and
From<&Laboratory>/From<&Laboratories> for CacheLaboratory/CacheLabsWrapper
in models/laboratory.rs. Simplify commands/login.rs to use .into()
conversions, removing the redundant to_cache_user() and to_cache_labs()
helper functions.

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

src/cli.rs

@@ -0,0 +1,114 @@
+use clap::{Parser, Subcommand};
+
+use crate::commands::config_subcommand::*;
+
+#[derive(Parser)]
+#[command(name = "mdrs")]
+#[command(about = "MDRS Rust CLI client", long_about = None)]
+pub struct Cli {
+    #[command(subcommand)]
+    pub command: Commands,
+}
+
+#[derive(Subcommand)]
+pub enum Commands {
+    /// Config management (create, update, list, delete)
+    #[command(subcommand)]
+    Config(ConfigSubcommand),
+    Login {
+        #[arg(short, long)]
+        username: Option<String>,
+        #[arg(short, long)]
+        password: Option<String>,
+        remote: String,
+    },
+    /// Logout and remove cached credentials for a remote
+    Logout {
+        remote: String,
+    },
+    Upload {
+        #[arg(short, long)]
+        recursive: bool,
+        #[arg(short = 's', long)]
+        skip_if_exists: bool,
+        local_path: String,
+        remote_path: String,
+    },
+    Download {
+        #[arg(short, long)]
+        recursive: bool,
+        #[arg(short = 's', long)]
+        skip_if_exists: bool,
+        #[arg(short = 'p', long)]
+        password: Option<String>,
+        #[arg(long)]
+        exclude: Vec<String>,
+        remote_path: String,
+        local_path: String,
+    },
+    Ls {
+        remote_path: String,
+        #[arg(short = 'p', long)]
+        password: Option<String>,
+        #[arg(short = 'J', long = "json")]
+        json: bool,
+        #[arg(short = 'r', long)]
+        recursive: bool,
+        #[arg(short = 'q', long)]
+        quiet: bool,
+    },
+    Whoami {
+        remote: String,
+    },
+    Labs {
+        remote: String,
+    },
+    Chacl {
+        /// Access level key: private, public, pw_open, cbs_open, 5kikan_open,
+        ///                    cbs_or_pw_open, 5kikan_or_pw_open, storage
+        access_level_key: String,
+        #[arg(short, long)]
+        recursive: bool,
+        #[arg(short = 'p', long)]
+        password: Option<String>,
+        remote_path: String,
+    },
+    Metadata {
+        #[arg(short = 'p', long)]
+        password: Option<String>,
+        remote_path: String,
+    },
+    Mkdir {
+        remote_path: String,
+    },
+    Rm {
+        #[arg(short, long)]
+        recursive: bool,
+        remote_path: String,
+    },
+    Mv {
+        src_path: String,
+        dest_path: String,
+    },
+    Cp {
+        #[arg(short, long)]
+        recursive: bool,
+        src_path: String,
+        dest_path: String,
+    },
+    /// Show metadata for a remote file
+    FileMetadata {
+        #[arg(short = 'p', long)]
+        password: Option<String>,
+        remote_path: String,
+    },
+    /// Show the version of this tool
+    Version,
+    /// Update this binary to the latest release
+    #[command(name = "selfupdate")]
+    SelfUpdate {
+        /// Skip the confirmation prompt
+        #[arg(short = 'y', long)]
+        yes: bool,
+    },
+}