feat: implement complete Rust version of mail2couch

- Add comprehensive Rust implementation matching Go functionality
- Configuration loading with automatic file discovery
- GNU-style command line parsing with clap (--config/-c, --max-messages/-m)
- CouchDB client integration with document storage and sync metadata
- IMAP client functionality with message fetching and parsing
- Folder filtering with wildcard pattern support (*, ?, [abc])
- Message filtering by subject, sender, and recipient keywords
- Incremental sync functionality with metadata tracking
- Bash completion generation matching Go implementation
- Cross-compatible document schemas and database structures
- Successfully tested with existing test environment

Note: TLS support and advanced email parsing features pending

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

rust/src/main.rs

@@ -1,7 +1,91 @@
-// Placeholder main.rs for Rust implementation
-// This will be implemented in the future
+use anyhow::Result;
+use env_logger::Env;
+use log::{error, info};
+use mail2couch::{
+    cli::parse_command_line,
+    config::Config,
+    sync::SyncCoordinator,
+};
+use std::process;
 
-fn main() {
-    println!("mail2couch Rust implementation - Coming Soon!");
-    println!("See the Go implementation in ../go/ for current functionality.");
+#[tokio::main]
+async fn main() {
+    // Initialize logging
+    env_logger::Builder::from_env(Env::default().default_filter_or("info")).init();
+
+    // Parse command line arguments
+    let args = parse_command_line();
+
+    // Run the main application
+    if let Err(e) = run(args).await {
+        error!("❌ Application failed: {}", e);
+        process::exit(1);
+    }
+}
+
+async fn run(args: mail2couch::config::CommandLineArgs) -> Result<()> {
+    info!("🚀 Starting mail2couch Rust implementation");
+
+    // Load configuration with automatic discovery
+    let (config, config_path) = Config::load_with_discovery(&args)?;
+    info!("Using configuration file: {}", config_path.display());
+
+    if let Some(max) = args.max_messages {
+        info!("Maximum messages per mailbox: {}", max);
+    } else {
+        info!("Maximum messages per mailbox: unlimited");
+    }
+
+    // Display configuration summary
+    print_config_summary(&config);
+
+    // Create sync coordinator
+    let mut coordinator = SyncCoordinator::new(config, args)?;
+
+    // Test all connections before starting sync
+    info!("Testing connections...");
+    coordinator.test_connections().await?;
+
+    // Perform synchronization
+    info!("Starting synchronization...");
+    let results = coordinator.sync_all_sources().await?;
+
+    // Print summary
+    coordinator.print_sync_summary(&results);
+
+    info!("🎉 mail2couch completed successfully!");
+    Ok(())
+}
+
+fn print_config_summary(config: &mail2couch::config::Config) {
+    info!("Configuration summary:");
+    info!("  CouchDB: {}", config.couch_db.url);
+    info!("  Mail sources: {}", config.mail_sources.len());
+
+    for (i, source) in config.mail_sources.iter().enumerate() {
+        let status = if source.enabled { "enabled" } else { "disabled" };
+        info!(
+            "    {}: {} ({}) - {} ({})",
+            i + 1,
+            source.name,
+            source.user,
+            source.host,
+            status
+        );
+
+        if source.enabled {
+            if !source.folder_filter.include.is_empty() {
+                info!("      Include folders: {:?}", source.folder_filter.include);
+            }
+            if !source.folder_filter.exclude.is_empty() {
+                info!("      Exclude folders: {:?}", source.folder_filter.exclude);
+            }
+            if source.message_filter.since.is_some() {
+                info!("      Since: {:?}", source.message_filter.since);
+            }
+            if !source.message_filter.subject_keywords.is_empty() {
+                info!("      Subject keywords: {:?}", source.message_filter.subject_keywords);
+            }
+        }
+    }
 }