refactor: Store pasted images in memory as base64 data URLs

- Remove save_clipboard_image and cleanup_temp_images backend commands
- Update FloatingPromptInput to store pasted images as data URLs in the prompt
- Update ImagePreview component to handle both file paths and data URLs
- Update extractImagePaths to properly handle quoted data URLs
- Update handleRemoveImage to handle data URL removal

This eliminates file system operations for pasted images and stores them directly
in the prompt as base64 data URLs (e.g., @"data:image/png;base64,...").
Images are now fully self-contained within the session without creating temp files.

src-tauri/src/main.rs

@@ -18,13 +18,13 @@ use commands::agents::{
 };
 use commands::claude::{
     cancel_claude_execution, check_auto_checkpoint, check_claude_version, cleanup_old_checkpoints,
-    cleanup_temp_images, clear_checkpoint_manager, continue_claude_code, create_checkpoint, execute_claude_code,
+    clear_checkpoint_manager, continue_claude_code, create_checkpoint, execute_claude_code,
     find_claude_md_files, fork_from_checkpoint, get_checkpoint_diff, get_checkpoint_settings,
     get_checkpoint_state_stats, get_claude_session_output, get_claude_settings, get_project_sessions,
     get_recently_modified_files, get_session_timeline, get_system_prompt, list_checkpoints,
     list_directory_contents, list_projects, list_running_claude_sessions, load_session_history,
     open_new_session, read_claude_md_file, restore_checkpoint, resume_claude_code,
-    save_claude_md_file, save_claude_settings, save_clipboard_image, save_system_prompt, search_files,
+    save_claude_md_file, save_claude_settings, save_system_prompt, search_files,
     track_checkpoint_message, track_session_messages, update_checkpoint_settings,
     get_hooks_config, update_hooks_config, validate_hook_command,
     ClaudeProcessState,
@@ -101,8 +101,6 @@ fn main() {
             find_claude_md_files,
             read_claude_md_file,
             save_claude_md_file,
-            save_clipboard_image,
-            cleanup_temp_images,
             load_session_history,
             execute_claude_code,
             continue_claude_code,