fix: handle SIGINT to restore terminal raw mode on Ctrl+C

Co-authored-by: aider (deepseek/deepseek-coder) <aider@aider.chat>

tui.c

@@ -2,6 +2,7 @@
 #include <ncurses.h>
 #include <string.h>
 #include <stdlib.h>
+#include <signal.h>
 
 #define GRID_ROWS 8
 #define GRID_COLS 8
@@ -32,6 +33,9 @@ static int state_to_color(ClipState state) {
         case CLIP_STOPPED: return COLOR_STOPPED;
         default: return COLOR_EMPTY;
     }
+    
+    // Install signal handler for Ctrl+C
+    signal(SIGINT, handle_sigint);
 }
 
 // Get clip index from grid position
@@ -138,6 +142,12 @@ static void draw_grid(void) {
     refresh();
 }
 
+static void handle_sigint(int sig) {
+    (void)sig;
+    tui_cleanup();
+    _exit(1);
+}
+
 void tui_init(Engine *engine) {
     g_engine = engine;
     
@@ -171,6 +181,10 @@ void tui_run(Engine *engine) {
     
     while (1) {
         int ch = getch();
+        if (ch == ERR) {
+            // getch returned error (e.g., signal interrupted)
+            break;
+        }
         
         switch (ch) {
             case 'h':
@@ -261,4 +275,7 @@ void tui_cleanup(void) {
     // Restore terminal settings
     curs_set(1);
     endwin();
+    
+    // Reset signal handler to default
+    signal(SIGINT, SIG_DFL);
 }