feat: add comprehensive README documentation and clean up configuration

## Documentation Enhancements
- Create comprehensive README with installation, configuration, and usage examples
- Add simple, advanced, and provider-specific configuration examples
- Document all features: incremental sync, wildcard patterns, keyword filtering, attachment support
- Include production deployment guidance and troubleshooting section
- Add architecture documentation with database structure and document format examples

## Configuration Cleanup
- Remove unnecessary `database` field from CouchDB configuration
- Add `m2c_` prefix to all CouchDB database names for better namespace isolation
- Update GenerateAccountDBName() to consistently prefix databases with `m2c_`
- Clean up all configuration examples to remove deprecated database field

## Test Environment Simplification
- Simplify test script structure to eliminate confusion and redundancy
- Remove redundant populate-test-messages.sh wrapper script
- Update run-tests.sh to be comprehensive automated test with cleanup
- Maintain clear separation: automated tests vs manual testing environment
- Update all test scripts to expect m2c-prefixed database names

## Configuration Examples Added
- config-simple.json: Basic single Gmail account setup
- config-advanced.json: Multi-account with complex filtering and different providers
- config-providers.json: Real-world configurations for Gmail, Outlook, Yahoo, iCloud

## Benefits
- Clear documentation for users from beginner to advanced
- Namespace isolation prevents database conflicts in shared CouchDB instances
- Simplified test workflow eliminates user confusion about which scripts to use
- Comprehensive examples cover common email provider configurations

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

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

go/mail/imap.go

@@ -86,6 +86,7 @@ func (c *ImapClient) ListMailboxes() ([]string, error) {
 // GetMessages retrieves messages from a specific mailbox with filtering support
 // Returns messages and a map of all current UIDs in the mailbox
 // maxMessages: 0 means no limit, > 0 limits the number of messages to fetch
+// since: if provided, only fetch messages newer than this date (for incremental sync)
 func (c *ImapClient) GetMessages(mailbox string, since *time.Time, maxMessages int, messageFilter *config.MessageFilter) ([]*Message, map[uint32]bool, error) {
 	// Select the mailbox
 	mbox, err := c.Select(mailbox, nil).Wait()
@@ -97,27 +98,80 @@ func (c *ImapClient) GetMessages(mailbox string, since *time.Time, maxMessages i
 		return []*Message{}, make(map[uint32]bool), nil
 	}
 
-	// For now, use a simpler approach to get all sequence numbers
 	var messages []*Message
 	currentUIDs := make(map[uint32]bool)
+
+	// First, get all current UIDs in the mailbox for sync purposes
+	allUIDsSet := imap.SeqSet{}
+	allUIDsSet.AddRange(1, mbox.NumMessages)
 	
-	// Determine how many messages to fetch
-	numToFetch := mbox.NumMessages
-	if maxMessages > 0 && int(numToFetch) > maxMessages {
-		numToFetch = uint32(maxMessages)
+	// Fetch UIDs for all messages to track current state
+	uidCmd := c.Fetch(allUIDsSet, &imap.FetchOptions{UID: true})
+	for {
+		msg := uidCmd.Next()
+		if msg == nil {
+			break
+		}
+		
+		data, err := msg.Collect()
+		if err != nil {
+			continue
+		}
+		
+		if data.UID != 0 {
+			currentUIDs[uint32(data.UID)] = true
+		}
 	}
+	uidCmd.Close()
 
-	if numToFetch == 0 {
-		return []*Message{}, currentUIDs, nil
-	}
-
-	// Create sequence set for fetching (1:numToFetch)
-	seqSet := imap.SeqSet{}
-	seqSet.AddRange(1, numToFetch)
-
-	// Track all sequence numbers (for sync we'll need to get UIDs later)
-	for i := uint32(1); i <= mbox.NumMessages; i++ {
-		currentUIDs[i] = true // Using sequence numbers for now
+	// Determine which messages to fetch based on since date
+	var seqSet imap.SeqSet
+	
+	if since != nil {
+		// Use IMAP SEARCH to find messages since the specified date
+		searchCriteria := &imap.SearchCriteria{
+			Since: *since,
+		}
+		
+		searchCmd := c.Search(searchCriteria, nil)
+		searchResults, err := searchCmd.Wait()
+		if err != nil {
+			log.Printf("IMAP SEARCH failed, falling back to fetch all: %v", err)
+			// Fall back to fetching all messages
+			numToFetch := mbox.NumMessages
+			if maxMessages > 0 && int(numToFetch) > maxMessages {
+				numToFetch = uint32(maxMessages)
+			}
+			seqSet.AddRange(mbox.NumMessages-numToFetch+1, mbox.NumMessages)
+		} else {
+			// Convert search results to sequence set
+			searchSeqNums := searchResults.AllSeqNums()
+			if len(searchSeqNums) == 0 {
+				return []*Message{}, currentUIDs, nil
+			}
+			
+			// Limit results if maxMessages is specified
+			if maxMessages > 0 && len(searchSeqNums) > maxMessages {
+				searchSeqNums = searchSeqNums[len(searchSeqNums)-maxMessages:]
+			}
+			
+			for _, seqNum := range searchSeqNums {
+				seqSet.AddNum(seqNum)
+			}
+		}
+	} else {
+		// No since date specified, fetch recent messages up to maxMessages
+		numToFetch := mbox.NumMessages
+		if maxMessages > 0 && int(numToFetch) > maxMessages {
+			numToFetch = uint32(maxMessages)
+		}
+		
+		if numToFetch == 0 {
+			return []*Message{}, currentUIDs, nil
+		}
+		
+		// Fetch the most recent messages
+		seqSet.AddRange(mbox.NumMessages-numToFetch+1, mbox.NumMessages)
 	}
 
 	// Fetch message data - get envelope and full message body