feat: Remove deprecated test files and enhance documentation for version 3.3.0 "Nexus Infinitum"

- Deleted obsolete test files: test_mime.go, test_mime_integration.go, and xmpp_client_upload_diagnosis.ipynb.
- Updated README.md to reflect the new version 3.3.0 "Nexus Infinitum" and its features.
- Added comprehensive release notes for version 3.3.0 detailing major enhancements and installation instructions.
- Introduced cleanup script to remove development artifacts while preserving production files.

test_enhanced_mime.go

@@ -1,71 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"mime"
-	"path/filepath"
-)
-
-// Enhanced MIME type support with additional mappings
-var customMimeTypes = map[string]string{
-	".m4a":  "audio/mp4",
-	".flac": "audio/flac",
-	".ogg":  "audio/ogg",
-	".webm": "video/webm",
-	".mkv":  "video/x-matroska",
-	".epub": "application/epub+zip",
-	".mobi": "application/x-mobipocket-ebook",
-	".apk":  "application/vnd.android.package-archive",
-	".deb":  "application/vnd.debian.binary-package",
-	".rpm":  "application/x-rpm",
-	".dmg":  "application/x-apple-diskimage",
-	".iso":  "application/x-iso9660-image",
-	".tar":  "application/x-tar",
-	".gz":   "application/gzip",
-	".bz2":  "application/x-bzip2",
-	".xz":   "application/x-xz",
-	".7z":   "application/x-7z-compressed",
-	".rar":  "application/vnd.rar",
-	".docx": "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
-	".xlsx": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
-	".pptx": "application/vnd.openxmlformats-officedocument.presentationml.presentation",
-}
-
-// GetMimeType returns the MIME type for a file extension
-func GetMimeType(filename string) string {
-	ext := filepath.Ext(filename)
-	
-	// First try standard Go mime detection
-	mimeType := mime.TypeByExtension(ext)
-	if mimeType != "" {
-		return mimeType
-	}
-	
-	// Try custom mappings
-	if customType, found := customMimeTypes[ext]; found {
-		return customType
-	}
-	
-	// Fallback to octet-stream
-	return "application/octet-stream"
-}
-
-func main() {
-	testFiles := []string{
-		"test.jpg", "document.pdf", "archive.zip", "video.mp4",
-		"audio.m4a", "book.epub", "package.deb", "disk.iso",
-		"unknown.xyz", "noext", "document.docx", "video.webm",
-	}
-	
-	fmt.Println("🔍 Enhanced MIME Type Detection:")
-	fmt.Println("┌─────────────────┬────────────────────────────────────────────────┐")
-	fmt.Println("│ File            │ MIME Type                                      │")
-	fmt.Println("├─────────────────┼────────────────────────────────────────────────┤")
-	
-	for _, file := range testFiles {
-		mimeType := GetMimeType(file)
-		fmt.Printf("│ %-15s │ %-46s │\n", file, mimeType)
-	}
-	
-	fmt.Println("└─────────────────┴────────────────────────────────────────────────┘")
-}