Fix Ctrl+C/D handling and add Unix socket control API for testing

Key changes:
- Fix keyboard input handling for control characters in GhosttyTerminalView
  - Set consumed_mods correctly (exclude Ctrl/Cmd from consumed mods)
  - Send unmodified character text for Ctrl+key combinations
  - Add unshifted_codepoint support for proper key encoding

- Add TerminalController with Unix socket API (/tmp/ghosttytabs.sock)
  - Commands: send, send_key, list_tabs, new_tab, close_tab, select_tab
  - Supports ctrl-c, ctrl-d, ctrl-z, enter, tab, escape, etc.

- Add Python test client and automated test suite
  - tests/ghosttytabs.py - Python client library
  - tests/test_ctrl_socket.py - Main Ctrl+C/D test suite (4 tests)
  - tests/test_signals_auto.py - Standalone PTY signal tests

- Update CLAUDE.md with socket API documentation and testing guide
- Update .gitignore for Python cache files

This fixes Ctrl+C/D not working in apps like claude-code, btop, opencode
while continuing to work in simpler apps like htop.

tests/test_ctrl_interactive.py

@@ -0,0 +1,121 @@
+#!/usr/bin/env python3
+"""
+Interactive test for Ctrl+C and Ctrl+D in GhosttyTabs terminal.
+
+This script tests that control signals are properly handled.
+Run this script inside the GhosttyTabs terminal.
+
+Tests:
+1. Ctrl+C (SIGINT) - Should interrupt a running process
+2. Ctrl+D (EOF) - Should signal end-of-file on stdin
+
+Usage:
+    python3 test_ctrl_interactive.py
+"""
+
+import signal
+import sys
+import os
+
+def test_ctrl_c():
+    """Test Ctrl+C signal handling"""
+    print("\n=== Test 1: Ctrl+C (SIGINT) ===")
+    print("This test will wait for you to press Ctrl+C.")
+    print("Press Ctrl+C now...")
+
+    received = [False]
+
+    def handler(signum, frame):
+        received[0] = True
+        print("\n✅ SUCCESS: SIGINT (Ctrl+C) received!")
+
+    old_handler = signal.signal(signal.SIGINT, handler)
+
+    try:
+        # Wait for up to 10 seconds for Ctrl+C
+        import time
+        for i in range(10):
+            if received[0]:
+                break
+            time.sleep(1)
+            if not received[0]:
+                print(f"   Waiting... ({10-i-1}s remaining)")
+
+        if not received[0]:
+            print("\n❌ FAILED: No SIGINT received within 10 seconds")
+            print("   Ctrl+C may not be working correctly.")
+            return False
+        return True
+    finally:
+        signal.signal(signal.SIGINT, old_handler)
+
+def test_ctrl_d():
+    """Test Ctrl+D (EOF) handling"""
+    print("\n=== Test 2: Ctrl+D (EOF) ===")
+    print("This test will read from stdin.")
+    print("Press Ctrl+D (on empty line) to send EOF...")
+    print("Type something and press Enter, then Ctrl+D on empty line:")
+
+    try:
+        lines = []
+        while True:
+            try:
+                line = input("> ")
+                lines.append(line)
+            except EOFError:
+                print("\n✅ SUCCESS: EOF (Ctrl+D) received!")
+                print(f"   Lines entered before EOF: {len(lines)}")
+                return True
+    except KeyboardInterrupt:
+        print("\n⚠️  Got Ctrl+C instead of Ctrl+D")
+        return False
+
+def main():
+    print("=" * 50)
+    print("GhosttyTabs Control Signal Test")
+    print("=" * 50)
+    print("\nThis script tests if Ctrl+C and Ctrl+D work correctly.")
+    print("Run this inside the GhosttyTabs terminal to verify the fix.\n")
+
+    # Check if running in a terminal
+    if not os.isatty(sys.stdin.fileno()):
+        print("Warning: Not running in a terminal")
+
+    results = []
+
+    # Test Ctrl+C
+    try:
+        results.append(("Ctrl+C (SIGINT)", test_ctrl_c()))
+    except Exception as e:
+        print(f"Error in Ctrl+C test: {e}")
+        results.append(("Ctrl+C (SIGINT)", False))
+
+    # Test Ctrl+D
+    try:
+        results.append(("Ctrl+D (EOF)", test_ctrl_d()))
+    except Exception as e:
+        print(f"Error in Ctrl+D test: {e}")
+        results.append(("Ctrl+D (EOF)", False))
+
+    # Summary
+    print("\n" + "=" * 50)
+    print("Test Results Summary")
+    print("=" * 50)
+
+    all_passed = True
+    for name, passed in results:
+        status = "✅ PASS" if passed else "❌ FAIL"
+        print(f"  {name}: {status}")
+        if not passed:
+            all_passed = False
+
+    print()
+    if all_passed:
+        print("All tests passed! Control signals are working correctly.")
+    else:
+        print("Some tests failed. Check the key input handling code.")
+
+    return 0 if all_passed else 1
+
+if __name__ == "__main__":
+    sys.exit(main())