refactor: remove webmail interface, focus on core mail storage functionality

- Remove obsolete CouchDB design documents (webmail.json, dashboard.json)
- Clean up webmail-related code from couch/couch.go (WebmailViews, CreateWebmailViews, etc.)
- Update documentation to focus on core mail-to-CouchDB storage functionality
- Add Future Plans section describing planned webmail viewer as separate component
- Apply go fmt formatting and ensure code quality standards
- Update test documentation to show raw CouchDB API access patterns
- Remove compiled binary from repository

This refactor simplifies the codebase to focus on its core purpose: efficiently
backing up emails from IMAP to CouchDB. The webmail interface will be developed
as a separate, optional component to maintain clean separation of concerns.

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

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

go/main.go

@@ -13,7 +13,7 @@ import (
 
 func main() {
 	args := config.ParseCommandLine()
-	
+
 	cfg, err := config.LoadConfigWithDiscovery(args)
 	if err != nil {
 		log.Fatalf("Failed to load configuration: %v", err)
@@ -33,12 +33,12 @@ func main() {
 
 		// Generate per-account database name
 		dbName := couch.GenerateAccountDBName(source.Name, source.User)
-		
+
 		// Ensure the account-specific database exists
 		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 		err = couchClient.EnsureDB(ctx, dbName)
 		cancel()
-		
+
 		if err != nil {
 			log.Printf("Could not ensure CouchDB database '%s' exists (is it running?): %v", dbName, err)
 			continue
@@ -111,7 +111,7 @@ func processImapSource(source *config.MailSource, couchClient *couch.Client, dbN
 		if syncMetadata != nil {
 			// Use last sync time for incremental sync
 			sinceDate = &syncMetadata.LastSyncTime
-			fmt.Printf("     Incremental sync since: %s (last synced %d messages)\n", 
+			fmt.Printf("     Incremental sync since: %s (last synced %d messages)\n",
 				sinceDate.Format("2006-01-02 15:04:05"), syncMetadata.MessageCount)
 		} else {
 			// First sync - use config since date if available