Add clean shutdown, wallet safety, and UI contrast fixes

Shutdown:
- Call litelib_shutdown() to stop Rust background threads on exit
- Add 15-second timeout on wallet save dialog to prevent hang on close
- Add litelib_shutdown FFI declaration in header and controller

UI Contrast (dragonx theme):
- Fix disabled buttons: white text was invisible on white background
- Add QWizard, QMessageBox, QTextBrowser, QPlainTextEdit styling for dark theme
- Add QCheckBox, QRadioButton, QDialogButtonBox contrast rules
- Fix seed word verification buttons: dark themed with explicit text color
- Fix chat bubbles: replace light backgrounds with dark themed colors
- Fix Terms of Service link color: #0000ff -> #6699ff for visibility
- Remove duplicate conflicting QLabel#lblMessage CSS rule

Add v1.1.0 release notes with checksums

lib/silentdragonxlitelib.h

@@ -15,6 +15,7 @@ extern char * litelib_execute             (const char* s, const char* args);
 extern void   litelib_rust_free_string    (char* s);
 extern char * blake3_PW                   (char* pw);
 extern bool litelib_check_server_online   (const char* server);
+extern void litelib_shutdown              (void);
 
 #ifdef __cplusplus
 }