Fix extra button to only work when OFF-hook and add greeting delay

Breaking Behavior Change:
- Extra button NOW only works when handset is OFF-hook (during call)
- Previous: worked when on-hook (idle) - REVERSED
- Reason: Button is for guests to trigger during their call/recording

New Feature - Greeting Delay:
- Add greeting_delay_seconds to config.json (0-10 seconds)
- Delays greeting playback after handset pickup
- Gives guests time to position phone comfortably
- Default: 0 (plays immediately, backward compatible)

Extra Button Logic:
- Only responds when phone_status == "off_hook"
- Ignored when phone is on-hook (idle)
- Can be pressed during greeting or recording
- Plays entire sound without interruption
- Useful for: "Press button to hear special message"

Greeting Delay Use Cases:
- Wedding: Give guests moment to settle in
- Events: Time to position phone comfortably
- Accessibility: Extra time for elderly guests
- Professional: Pause before message delivery

Configuration:
{
  "system": {
    "greeting_delay_seconds": 2,  // 2 second pause
    "extra_button_sound": "surprise.wav"
  }
}

Console Output:
- "Extra button ignored - phone is on hook" (when idle)
- "Waiting X seconds before greeting..." (delay active)
- "=== Extra button pressed ===" (during call)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

rotary_phone_web.py

@@ -305,13 +305,13 @@ class RotaryPhone:
         }
     
     def play_extra_button_sound(self):
-        """Play sound when extra button is pressed (only when on-hook)"""
+        """Play sound when extra button is pressed (only when off-hook/in call)"""
         if not EXTRA_BUTTON_ENABLED:
             return
 
-        # Only play if phone is on hook (not in use)
-        if self.phone_status != "on_hook":
-            print("Extra button ignored - phone is off hook")
+        # Only play if phone is OFF hook (during a call)
+        if self.phone_status != "off_hook":
+            print("Extra button ignored - phone is on hook")
             return
 
         button_sound = self.get_extra_button_sound_path()
@@ -348,6 +348,12 @@ class RotaryPhone:
                     self.phone_status = "off_hook"
                     print("\n=== Handset picked up ===")
 
+                    # Apply greeting delay if configured
+                    greeting_delay = SYS_CONFIG['system'].get('greeting_delay_seconds', 0)
+                    if greeting_delay > 0:
+                        print(f"Waiting {greeting_delay} seconds before greeting...")
+                        time.sleep(greeting_delay)
+
                     # Play active greeting message
                     greeting_file = self.get_active_greeting_path()
                     self.play_sound_file(greeting_file)