feat: implement real IMAP message parsing with native CouchDB attachments

- Replace placeholder message generation with actual IMAP message fetching using go-message library
- Add per-account CouchDB databases for better organization and isolation
- Implement native CouchDB attachment storage with proper revision management
- Add command line argument parsing with --max-messages flag for controlling message processing limits
- Support both sync and archive modes with proper document synchronization
- Add comprehensive test environment with Podman containers (GreenMail IMAP server + CouchDB)
- Implement full MIME multipart parsing for proper body and attachment extraction
- Add TLS and plain IMAP connection support based on port configuration
- Update configuration system to support sync vs archive modes
- Create test scripts and sample data for development and testing

Key technical improvements:
- Real email envelope and header processing with go-imap v2 API
- MIME Content-Type and Content-Disposition parsing for attachment detection
- CouchDB document ID generation using mailbox_uid format for uniqueness
- Duplicate detection and prevention to avoid re-storing existing messages
- Proper error handling and connection management for IMAP operations

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

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

test/run-tests.sh

@@ -0,0 +1,128 @@
+#!/bin/bash
+
+# Run integration tests with test containers
+
+set -e
+
+cd "$(dirname "$0")"
+
+echo "🚀 Starting mail2couch integration tests..."
+
+# Colors for output
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+NC='\033[0m' # No Color
+
+# Function to print colored output
+print_status() {
+    echo -e "${GREEN}[INFO]${NC} $1"
+}
+
+print_warning() {
+    echo -e "${YELLOW}[WARN]${NC} $1"
+}
+
+print_error() {
+    echo -e "${RED}[ERROR]${NC} $1"
+}
+
+# Cleanup function
+cleanup() {
+    print_status "Cleaning up test containers..."
+    podman-compose -f podman-compose.yml down -v 2>/dev/null || true
+}
+
+# Set up cleanup trap
+trap cleanup EXIT
+
+# Start containers
+print_status "Starting test containers..."
+podman-compose -f podman-compose.yml up -d
+
+# Wait for containers to be ready
+print_status "Waiting for containers to be ready..."
+sleep 10
+
+# Check if CouchDB is ready
+print_status "Checking CouchDB connectivity..."
+timeout=30
+while ! curl -s http://localhost:5984/_up > /dev/null 2>&1; do
+    timeout=$((timeout - 1))
+    if [ $timeout -le 0 ]; then
+        print_error "CouchDB failed to start within 30 seconds"
+        exit 1
+    fi
+    sleep 1
+done
+print_status "CouchDB is ready!"
+
+# Check if IMAP server is ready
+print_status "Checking IMAP server connectivity..."
+timeout=30
+while ! nc -z localhost 3143 > /dev/null 2>&1; do
+    timeout=$((timeout - 1))
+    if [ $timeout -le 0 ]; then
+        print_error "IMAP server failed to start within 30 seconds"
+        exit 1
+    fi
+    sleep 1
+done
+print_status "IMAP server is ready!"
+
+# Populate test messages
+print_status "Populating test messages..."
+./populate-test-messages.sh
+
+# Build mail2couch
+print_status "Building mail2couch..."
+cd ../go
+go build -o mail2couch .
+cd ../test
+
+# Run mail2couch with test configuration
+print_status "Running mail2couch with test configuration..."
+../go/mail2couch -config config-test.json
+
+# Verify results
+print_status "Verifying test results..."
+
+# Check CouchDB databases were created
+EXPECTED_DBS=("test_user_1" "test_sync_user" "test_archive_user")
+
+for db in "${EXPECTED_DBS[@]}"; do
+    if curl -s "http://admin:password@localhost:5984/$db" | grep -q "\"db_name\":\"$db\""; then
+        print_status "✅ Database '$db' created successfully"
+    else
+        print_error "❌ Database '$db' was not created"
+        exit 1
+    fi
+done
+
+# Check document counts
+for db in "${EXPECTED_DBS[@]}"; do
+    doc_count=$(curl -s "http://admin:password@localhost:5984/$db" | grep -o '"doc_count":[0-9]*' | cut -d':' -f2)
+    if [ "$doc_count" -gt 0 ]; then
+        print_status "✅ Database '$db' contains $doc_count documents"
+    else
+        print_warning "⚠️ Database '$db' contains no documents"
+    fi
+done
+
+# Test sync mode by running again (should show removed documents if any)
+print_status "Running mail2couch again to test sync behavior..."
+../go/mail2couch -config config-test.json
+
+print_status "🎉 All tests completed successfully!"
+
+# Show summary
+print_status "Test Summary:"
+echo "  - IMAP Server: localhost:143"
+echo "  - CouchDB: http://localhost:5984"
+echo "  - Test accounts: testuser1, syncuser, archiveuser"
+echo "  - Databases created: ${EXPECTED_DBS[*]}"
+echo ""
+echo "You can now:"
+echo "  - Access CouchDB at http://localhost:5984/_utils"
+echo "  - Connect to IMAP at localhost:143"
+echo "  - Run manual tests with: ../go/mail2couch -config config-test.json"