feat(01-03): wire complete startup-to-shutdown pipeline in main.rs

- All four modules declared: mod app, config, signals, terminal
- Pre-terminal phase: login shell detection, CLI parse, config load
- Terminal phase: panic hook installed first, then signals, then terminal init
- Event loop: App::new receives is_login_shell and app_config; run_event_loop runs
- Shutdown: restore_terminal() called before show_goodbye() in all exit paths
- BrokenPipe from event loop exits silently (LIFE-04)
- Unexpected I/O errors logged to stderr after terminal restore

src/main.rs

@@ -4,10 +4,14 @@ mod signals;
 mod terminal;
 
 fn main() {
+    // ── PRE-TERMINAL PHASE ────────────────────────────────────────────────────
+    // Errors here use normal eprintln! — the terminal is not yet in raw mode.
+
     // 1. Detect login shell BEFORE stripping argv[0]
+    //    POSIX: kernel prefixes argv[0] with '-' for login shells.
     let is_login_shell = config::detect_login_shell();
 
-    // 2. Parse CLI (strips dash from argv[0] internally)
+    // 2. Parse CLI (strips the leading dash from argv[0] before clap sees it)
     let cli = config::parse_cli();
 
     // 3. Resolve config path and load config
@@ -20,8 +24,65 @@ fn main() {
         }
     };
 
-    // Phase 1 placeholder: print loaded config for verification
-    // This will be replaced by terminal init + event loop in Plan 03
-    println!("Config loaded: {:?}", app_config);
-    println!("Login shell: {}", is_login_shell);
+    // ── TERMINAL PHASE ────────────────────────────────────────────────────────
+    // Install safety envelope BEFORE terminal init so panics during init are caught.
+
+    // 4. Install panic hook first — covers panics during terminal init itself
+    terminal::install_panic_hook();
+
+    // 5. Register signal handlers before terminal init — covers early SIGHUP
+    //    (e.g. SSH disconnect between login shell launch and first draw)
+    let signal_flags = match signals::register_signals() {
+        Ok(s) => s,
+        Err(e) => {
+            eprintln!("SYSTEM ERROR: Cannot register signal handlers: {}", e);
+            std::process::exit(1);
+        }
+    };
+
+    // 6. Initialize terminal (enables raw mode, clears screen, sets Viewport::Fullscreen)
+    let mut term = match terminal::init_terminal() {
+        Ok(t) => t,
+        Err(e) => {
+            eprintln!("SYSTEM ERROR: Cannot initialize terminal: {}", e);
+            std::process::exit(1);
+        }
+    };
+
+    // ── EVENT LOOP PHASE ──────────────────────────────────────────────────────
+
+    // 7. Create app state and run the event loop
+    //    app_config is stored in App for Phase 2+ use (vault_path, theme).
+    let mut app_state = app::App::new(is_login_shell, app_config);
+    let shutdown_reason = app_state.run_event_loop(&mut term, &signal_flags);
+
+    // ── SHUTDOWN PHASE ────────────────────────────────────────────────────────
+    // Terminal must be restored in EVERY exit path below.
+
+    // 8. Restore terminal — always, regardless of how we got here.
+    //    Must happen BEFORE show_goodbye() since goodbye prints to stdout.
+    terminal::restore_terminal();
+
+    // 9. Handle the shutdown reason
+    match shutdown_reason {
+        Ok(app::ShutdownReason::UserQuit) => {
+            // User deliberately exited — show BBS goodbye message
+            app::show_goodbye();
+        }
+        Ok(app::ShutdownReason::Signal) => {
+            // SIGHUP or SIGTERM — SSH disconnect or graceful OS shutdown.
+            // Exit silently: there may be nobody on the other end to see a message.
+        }
+        Err(e) => {
+            // I/O error from the event loop
+            if e.kind() == std::io::ErrorKind::BrokenPipe {
+                // SSH connection closed while we were writing — silent exit (LIFE-04).
+                // Terminal is already restored above; just exit quietly.
+            } else {
+                // Unexpected I/O error — log to stderr after terminal restore
+                eprintln!("SYSTEM ERROR: {}", e);
+                std::process::exit(1);
+            }
+        }
+    }
 }