feat: add multiple productivity features and UI enhancements (#68)

## Summary

This PR adds a collection of productivity features and UI enhancements to improve the Hikari Desktop experience:

### New Features
- **Clipboard History** (#25) - Track and manage copied code snippets with language detection, search, filtering, and pinning
- **Quick Actions Panel** (#15) - Buttons for common quick actions like "Review PR", "Run tests", "Explain file", with customizable actions
- **Git Integration Panel** (#24) - View current branch, changed/staged files, quick git actions (commit, push, pull), and branch management
- **Session Import/Export** (#8) - Export conversations to JSON and import previously saved sessions
- **Snippet Library** (#22) - Save and reuse common prompts with categories and quick insert
- **Session History** (#14) - Auto-save conversations with browsable history and search
- **High Contrast Mode** (#20) - Accessibility theme with improved visibility
- **Minimize to System Tray** (#11) - System tray support with right-click menu

### UI Enhancements
- Trans-pride gradient theme applied across UI elements
- Copy button added to code blocks
- Linter formatting and eslint-disable comments for cleaner code

## Closes

Closes #8
Closes #11
Closes #14
Closes #15
Closes #20
Closes #22
Closes #24
Closes #25
Closes #34
Closes #35
Closes #36
Closes #37
Closes #69
Closes #70

## Test Plan

- [ ] Verify clipboard history captures code from code block copy buttons
- [ ] Verify clipboard history captures manually selected text from terminal
- [ ] Test snippet library CRUD operations and insertion
- [ ] Test quick actions panel with default and custom actions
- [ ] Test git panel shows correct status, branch, and performs git operations
- [ ] Test session history auto-save and restore
- [ ] Test session import/export roundtrip
- [ ] Verify high contrast mode provides adequate contrast
- [ ] Test minimize to tray functionality and tray menu
- [ ] Verify trans-pride gradient theme displays correctly in all themes

---
*✨ This PR was created with help from Hikari~ 🌸*

Co-authored-by: Naomi Carrigan <commits@nhcarrigan.com>
Reviewed-on: #68
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

src-tauri/src/lib.rs

@@ -1,10 +1,16 @@
 mod achievements;
 mod bridge_manager;
+mod clipboard;
 mod commands;
 mod config;
+mod git;
 mod notifications;
+mod quick_actions;
+mod sessions;
+mod snippets;
 mod stats;
 mod temp_manager;
+mod tray;
 mod types;
 mod vbs_notification;
 mod windows_toast;
@@ -12,10 +18,17 @@ mod wsl_bridge;
 mod wsl_notifications;
 
 use bridge_manager::create_shared_bridge_manager;
+use clipboard::*;
 use commands::load_saved_achievements;
 use commands::*;
+use git::*;
 use notifications::*;
+use quick_actions::*;
+use sessions::*;
+use snippets::*;
+use tauri::Manager;
 use temp_manager::create_shared_temp_manager;
+use tray::{setup_tray, should_minimize_to_tray};
 use vbs_notification::*;
 use windows_toast::*;
 use wsl_notifications::*;
@@ -34,6 +47,7 @@ pub fn run() {
         .plugin(tauri_plugin_os::init())
         .plugin(tauri_plugin_http::init())
         .plugin(tauri_plugin_clipboard_manager::init())
+        .plugin(tauri_plugin_fs::init())
         .manage(bridge_manager.clone())
         .manage(temp_manager.clone())
         .setup(move |app| {
@@ -47,6 +61,27 @@ pub fn run() {
                 }
             }
 
+            // Set up system tray
+            if let Err(e) = setup_tray(app.handle()) {
+                eprintln!("Failed to set up system tray: {}", e);
+            }
+
+            // Handle window close event for minimize to tray
+            let main_window = app.get_webview_window("main").unwrap();
+            main_window.on_window_event({
+                let app_handle = app.handle().clone();
+                move |event| {
+                    if let tauri::WindowEvent::CloseRequested { api, .. } = event {
+                        if should_minimize_to_tray(&app_handle) {
+                            api.prevent_close();
+                            if let Some(window) = app_handle.get_webview_window("main") {
+                                let _ = window.hide();
+                            }
+                        }
+                    }
+                }
+            });
+
             Ok(())
         })
         .invoke_handler(tauri::generate_handler![
@@ -60,6 +95,7 @@ pub fn run() {
             get_config,
             save_config,
             get_usage_stats,
+            get_persisted_stats,
             load_saved_achievements,
             answer_question,
             send_windows_notification,
@@ -78,6 +114,43 @@ pub fn run() {
             cleanup_all_temp_files,
             cleanup_orphaned_temp_files,
             get_file_size,
+            list_sessions,
+            save_session,
+            load_session,
+            delete_session,
+            search_sessions,
+            clear_all_sessions,
+            list_snippets,
+            save_snippet,
+            delete_snippet,
+            get_snippet_categories,
+            reset_default_snippets,
+            list_quick_actions,
+            save_quick_action,
+            delete_quick_action,
+            reset_default_quick_actions,
+            git_status,
+            git_diff,
+            git_branches,
+            git_checkout,
+            git_stage,
+            git_unstage,
+            git_stage_all,
+            git_commit,
+            git_push,
+            git_pull,
+            git_fetch,
+            git_log,
+            git_discard,
+            git_create_branch,
+            list_clipboard_entries,
+            capture_clipboard,
+            delete_clipboard_entry,
+            toggle_pin_clipboard_entry,
+            clear_clipboard_history,
+            search_clipboard_entries,
+            get_clipboard_languages,
+            update_clipboard_language,
         ])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");