feat: add 4 new voice effects (echo, robot, chorus, tremolo)

- Removed MAX_ACTIVE_EFFECTS limit (effects unlimited)
- Added echo effect (0-100%): spatial delay/reverb
- Added robot effect (0-100%): ring modulation voice
- Added chorus effect (0-100%): multiple voices effect
- Added tremolo depth (0.0-1.0) and rate (0.0-10.0 Hz): amplitude modulation
- Effects apply in order: pitch → speed → echo → chorus → tremolo → robot
- Updated /effects command with all 7 effect choices
- Updated /effects list to display all 7 effects with emojis
- Updated warning system: warns when > 2 active effects
- Added validation and formatting for all new effects
- Updated voice_manager.py to handle all 7 effect storage/loading

Note: Cancel button for processing >10s not yet implemented
Note: Queue system needs updating to handle all effect parameters

bot.py

@@ -141,6 +141,11 @@ class TTSBot(commands.Bot):
         @app_commands.choices(effect_name=[
             app_commands.Choice(name="pitch", value="pitch"),
             app_commands.Choice(name="speed", value="speed"),
+            app_commands.Choice(name="echo", value="echo"),
+            app_commands.Choice(name="robot", value="robot"),
+            app_commands.Choice(name="chorus", value="chorus"),
+            app_commands.Choice(name="tremolo_depth", value="tremolo_depth"),
+            app_commands.Choice(name="tremolo_rate", value="tremolo_rate"),
         ])
         async def effects_command(
             interaction: discord.Interaction,
@@ -174,12 +179,42 @@ class TTSBot(commands.Bot):
         lines.append(f"⚡ **Speed**: {speed_val}")
         lines.append(f"   {speed_desc}\n")
 
+        # Echo
+        echo_desc = AudioEffects.get_effect_description("echo")
+        echo_val = AudioEffects.format_effect_value("echo", effects["echo"])
+        lines.append(f"🔊 **Echo**: {echo_val}")
+        lines.append(f"   {echo_desc}\n")
+
+        # Robot
+        robot_desc = AudioEffects.get_effect_description("robot")
+        robot_val = AudioEffects.format_effect_value("robot", effects["robot"])
+        lines.append(f"🤖 **Robot**: {robot_val}")
+        lines.append(f"   {robot_desc}\n")
+
+        # Chorus
+        chorus_desc = AudioEffects.get_effect_description("chorus")
+        chorus_val = AudioEffects.format_effect_value("chorus", effects["chorus"])
+        lines.append(f"🎶 **Chorus**: {chorus_val}")
+        lines.append(f"   {chorus_desc}\n")
+
+        # Tremolo Depth
+        tremolo_depth_desc = AudioEffects.get_effect_description("tremolo_depth")
+        tremolo_depth_val = AudioEffects.format_effect_value("tremolo_depth", effects["tremolo_depth"])
+        lines.append(f"〰️ **Tremolo Depth**: {tremolo_depth_val}")
+        lines.append(f"   {tremolo_depth_desc}\n")
+
+        # Tremolo Rate
+        tremolo_rate_desc = AudioEffects.get_effect_description("tremolo_rate")
+        tremolo_rate_val = AudioEffects.format_effect_value("tremolo_rate", effects["tremolo_rate"])
+        lines.append(f"📳 **Tremolo Rate**: {tremolo_rate_val}")
+        lines.append(f"   {tremolo_rate_desc}\n")
+
         # Active count warning
-        lines.append(f"**Active Effects**: {active_count}/{AudioEffects.MAX_ACTIVE_EFFECTS}")
-        if active_count >= AudioEffects.MAX_ACTIVE_EFFECTS:
-            lines.append("⚠️ Max effects reached. More effects = slower processing time.")
+        lines.append(f"**Active Effects**: {active_count}")
+        if active_count > 2:
+            lines.append("⚠️ You have more than 2 active effects. Processing may be slower!")
         elif active_count > 0:
-            lines.append(f"ℹ️ You can add {AudioEffects.MAX_ACTIVE_EFFECTS - active_count} more effect(s).")
+            lines.append("ℹ️ Add more effects for fun variations (may slow processing)")
 
         lines.append(f"\n*Use `/effects set <effect> <value>` to change settings*")
         lines.append(f"*Use `/effects reset` to clear all effects*")