feat(cli): add interactive email import tool for EML, MBOX, and Thunderbird

- Implement `bichonctl` interactive CLI using `dialoguer`.
- Support recursive EML directory scanning with folder structure preservation.
- Support single MBOX file streaming import.
- Support Thunderbird profile import with automatic `.sbd` hierarchy detection.
- Add batch processing (Base64 encoding & batch API requests) for improved performance.

src/modules/cli/eml/mod.rs

@@ -0,0 +1,133 @@
+use std::{
+    collections::HashMap,
+    fs,
+    path::{Path, PathBuf},
+};
+
+use console::style;
+use dialoguer::{theme::ColorfulTheme, Input};
+use mail_parser::MessageParser;
+use reqwest::Client;
+
+use crate::{
+    base64_encode_url_safe,
+    modules::cli::{sender::send_batch_request, BichonCtlConfig},
+};
+
+pub async fn handle_eml_directory_import(
+    config: &BichonCtlConfig,
+    account_id: u64,
+    theme: &ColorfulTheme,
+) {
+    let root_str: String = Input::with_theme(theme)
+        .with_prompt("Enter the ROOT directory to scan for .eml files")
+        .validate_with(|input: &String| {
+            let p = std::path::Path::new(input);
+            if p.exists() && p.is_dir() {
+                Ok(())
+            } else {
+                Err("Directory not found.")
+            }
+        })
+        .interact_text()
+        .unwrap();
+
+    let root_path = std::path::PathBuf::from(root_str);
+    let mut tasks: HashMap<String, Vec<PathBuf>> = HashMap::new();
+    println!(
+        "{}",
+        style("🔍 Scanning recursively using std::fs...").dim()
+    );
+    if let Err(e) = scan_dir(&root_path, &root_path, &mut tasks) {
+        eprintln!("Error scanning directory: {}", e);
+        return;
+    }
+
+    if tasks.is_empty() {
+        println!("{}", style("No .eml files found.").yellow());
+    } else {
+        process_and_upload(config, account_id, tasks).await;
+    }
+}
+
+fn scan_dir(
+    root: &Path,
+    current: &Path,
+    tasks: &mut HashMap<String, Vec<PathBuf>>,
+) -> std::io::Result<()> {
+    if current.is_dir() {
+        for entry in fs::read_dir(current)? {
+            let entry = entry?;
+            let path = entry.path();
+
+            if path.is_dir() {
+                scan_dir(root, &path, tasks)?;
+            } else if path.is_file() {
+                if path.extension().and_then(|s| s.to_str()) == Some("eml") {
+                    let rel_path = path.strip_prefix(root).unwrap_or(Path::new(""));
+                    let mailbox_name = rel_path
+                        .parent()
+                        .map(|p| p.to_string_lossy().replace('\\', "/"))
+                        .unwrap_or_default();
+                    let folder = if mailbox_name.is_empty() {
+                        "Inbox".to_string()
+                    } else {
+                        mailbox_name
+                    };
+                    tasks.entry(folder).or_insert_with(|| Vec::new()).push(path);
+                }
+            }
+        }
+    }
+    Ok(())
+}
+
+async fn process_and_upload(
+    config: &BichonCtlConfig,
+    account_id: u64,
+    tasks: HashMap<String, Vec<PathBuf>>,
+) {
+    let client = Client::new();
+    let batch_size = 50;
+
+    for (mailbox, files) in tasks {
+        println!("\n🚀 Processing mailbox: {}", style(&mailbox).cyan().bold());
+
+        let mut current_batch = Vec::new();
+
+        for file_path in files {
+            let body = match fs::read(&file_path) {
+                Ok(b) => b,
+                Err(e) => {
+                    eprintln!(
+                        "  {} Failed to read file {:?}: {}",
+                        style("✘").red(),
+                        file_path,
+                        e
+                    );
+                    continue;
+                }
+            };
+
+            if MessageParser::new().parse(&body).is_some() {
+                let b64_content = base64_encode_url_safe!(&body);
+                current_batch.push(b64_content);
+
+                if current_batch.len() >= batch_size {
+                    let to_send = current_batch;
+                    current_batch = Vec::with_capacity(batch_size);
+                    send_batch_request(&client, config, account_id, &mailbox, to_send).await;
+                }
+            } else {
+                eprintln!(
+                    "  {} Invalid format, skipping: {:?}",
+                    style("⚠").yellow(),
+                    file_path
+                );
+            }
+        }
+        if !current_batch.is_empty() {
+            send_batch_request(&client, config, account_id, &mailbox, current_batch).await;
+        }
+    }
+}