feat: add native clipboard support for screenshot paste (#67)

## Summary
- Adds Tauri clipboard-manager plugin to read images from native clipboard
- Falls back to native clipboard when WebView clipboard API returns empty (fixes screenshot paste)
- Allows sending messages with just attachments (no text required)
- Logs attached files to output with 📎 emoji

## Test plan
- [ ] Build and run the app natively on Windows
- [ ] Copy a screenshot (Win+Shift+S) and paste in the chat input
- [ ] Verify the screenshot appears as an attachment preview
- [ ] Send the attachment and verify Claude receives the file path
- [ ] Test sending a message with only an attachment (no text)
- [ ] Verify the 📎 log line shows the attached filename

**Note:** Paste will not work in WSLg dev environment due to clipboard isolation - needs native Windows build to test.

✨ This PR was created with help from Hikari~ 🌸

Co-authored-by: Hikari <hikari@nhcarrigan.com>
Reviewed-on: #67
Co-authored-by: Naomi Carrigan <commits@nhcarrigan.com>
Co-committed-by: Naomi Carrigan <commits@nhcarrigan.com>

src-tauri/src/lib.rs

@@ -4,6 +4,7 @@ mod commands;
 mod config;
 mod notifications;
 mod stats;
+mod temp_manager;
 mod types;
 mod vbs_notification;
 mod windows_toast;
@@ -14,6 +15,7 @@ use bridge_manager::create_shared_bridge_manager;
 use commands::load_saved_achievements;
 use commands::*;
 use notifications::*;
+use temp_manager::create_shared_temp_manager;
 use vbs_notification::*;
 use windows_toast::*;
 use wsl_notifications::*;
@@ -21,6 +23,7 @@ use wsl_notifications::*;
 #[cfg_attr(mobile, tauri::mobile_entry_point)]
 pub fn run() {
     let bridge_manager = create_shared_bridge_manager();
+    let temp_manager = create_shared_temp_manager().expect("Failed to create temp file manager");
 
     tauri::Builder::default()
         .plugin(tauri_plugin_dialog::init())
@@ -30,10 +33,20 @@ pub fn run() {
         .plugin(tauri_plugin_notification::init())
         .plugin(tauri_plugin_os::init())
         .plugin(tauri_plugin_http::init())
+        .plugin(tauri_plugin_clipboard_manager::init())
         .manage(bridge_manager.clone())
+        .manage(temp_manager.clone())
         .setup(move |app| {
             // Initialize the app handle in the bridge manager
             bridge_manager.lock().set_app_handle(app.handle().clone());
+
+            // Clean up any orphaned temp files from previous sessions
+            if let Ok(count) = temp_manager.lock().cleanup_orphaned_files() {
+                if count > 0 {
+                    println!("Cleaned up {} orphaned temp files", count);
+                }
+            }
+
             Ok(())
         })
         .invoke_handler(tauri::generate_handler![
@@ -58,6 +71,13 @@ pub fn run() {
             validate_directory,
             list_skills,
             check_for_updates,
+            save_temp_file,
+            register_temp_file,
+            get_temp_files,
+            cleanup_temp_files,
+            cleanup_all_temp_files,
+            cleanup_orphaned_temp_files,
+            get_file_size,
         ])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");