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/Cargo.toml

@@ -29,8 +29,9 @@ anyhow = "1.0"
 # Configuration
 config = "0.13"
 
-# IMAP client (when implementing IMAP functionality)
-# async-imap = "0.9"  # Commented out for now due to compatibility issues
+# IMAP client for email retrieval (using async-std compatible version)
+async-imap = "0.9"
+async-std = { version = "1.12", features = ["attributes"] }
 
 # Logging
 log = "0.4"
@@ -39,9 +40,16 @@ env_logger = "0.10"
 # CLI argument parsing
 clap = { version = "4.0", features = ["derive"] }
 
+# File system utilities
+dirs = "5.0"
+
+# Pattern matching for folder filters
+glob = "0.3"
+
 [dev-dependencies]
 # Testing utilities
 tokio-test = "0.4"
+tempfile = "3.0"
 
 [lib]
 name = "mail2couch"