feat: scaffold Tauri 2.0 backend foundation

Set up the Rust backend for Mission Control using Tauri 2.0:

Cargo Configuration:
- Cargo.toml: Tauri 2.0, serde, thiserror, tracing, mockall
  - Library crate (mission_control_lib) for testability
  - Binary crate for Tauri entry point
- Cargo.lock: Pinned dependencies for reproducible builds

Tauri Configuration (tauri.conf.json):
- App identifier: com.mission-control.app
- Window: 800x600, centered, hiddenTitle for clean macOS look
- Shell plugin scoped to lore, br, bv commands only
- Tray icon configured for background operation

Application Bootstrap:
- src/main.rs: Minimal entry point, delegates to lib
- src/lib.rs: Tracing setup, plugin registration, command handlers
  - Debug mode: auto-opens devtools
  - Safe window lookup (no unwrap panic)
- build.rs: Tauri build script for codegen

Architecture: The lib/bin split enables unit testing the Tauri
command handlers without launching the full app.

src-tauri/src/lib.rs

@@ -0,0 +1,47 @@
+//! Mission Control - ADHD-centric personal productivity hub
+//!
+//! This crate provides the Rust backend for Mission Control, handling:
+//! - CLI integration with lore (GitLab data) and br (beads task management)
+//! - GitLab → Beads bridge (creating beads from GitLab events)
+//! - Decision logging and state persistence
+//! - File watching for automatic sync
+
+pub mod commands;
+pub mod data;
+
+use tauri::Manager;
+use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
+
+/// Initialize the Tauri application with all plugins and commands.
+#[cfg_attr(mobile, tauri::mobile_entry_point)]
+pub fn run() {
+    // Initialize tracing
+    tracing_subscriber::registry()
+        .with(
+            tracing_subscriber::EnvFilter::try_from_default_env()
+                .unwrap_or_else(|_| "mission_control=debug".into()),
+        )
+        .with(tracing_subscriber::fmt::layer())
+        .init();
+
+    tracing::info!("Starting Mission Control");
+
+    tauri::Builder::default()
+        .plugin(tauri_plugin_shell::init())
+        .setup(|app| {
+            #[cfg(debug_assertions)]
+            {
+                // Open devtools in debug mode
+                if let Some(window) = app.get_webview_window("main") {
+                    window.open_devtools();
+                }
+            }
+            Ok(())
+        })
+        .invoke_handler(tauri::generate_handler![
+            commands::greet,
+            commands::get_lore_status,
+        ])
+        .run(tauri::generate_context!())
+        .expect("error while running tauri application");
+}