refactor(client): decouple dialogue_box from GameState and AudioManager (#558)

Replace 3 direct GameState.dialogue_active mutations and all
AudioManager.apply_dip/clear_dip calls with signals:
dialogue_state_changed, audio_dip_requested, audio_dip_cleared.
dialogue_box.gd now has zero references to GameState or AudioManager.
main.gd wires coordinator handlers in _ready() (D-020).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/ui/dialogue_box.gd

@@ -15,6 +15,11 @@ signal dialogue_dismissed  # Walk-away or conversation end
 signal confrontation_monologue(text: String, duration: float)  # D-063: beat monologue
 signal pause_requested   # D-061: auto-pause — main.gd routes through input recording (#507)
 signal unpause_requested  # D-061: auto-unpause
+# D-020 (#558): Decoupled signals — dialogue_box emits, main.gd (coordinator) handles.
+# Replaces direct GameState.dialogue_active mutation and AudioManager calls.
+signal dialogue_state_changed(active: bool)
+signal audio_dip_requested(profile: String)
+signal audio_dip_cleared
 
 @onready var panel: PanelContainer = $PanelContainer
 @onready var dialogue_log: RichTextLabel = $PanelContainer/MarginContainer/VBoxContainer/DialogueLog
@@ -286,10 +291,10 @@ func show_dialogue(npc_name: String, speech: String, options: Array = []) -> voi
 	# Show panel
 	_ensure_visible()
 	mouse_filter = Control.MOUSE_FILTER_STOP
-	GameState.dialogue_active = true  # D-064: block movement while in conversation
+	dialogue_state_changed.emit(true)  # D-064: coordinator blocks movement
 
-	# D-069: Dialogue dip
-	AudioManager.apply_dip("dialogue")
+	# D-069: Dialogue dip — coordinator routes to AudioManager
+	audio_dip_requested.emit("dialogue")
 
 	# D-061: auto-pause — signal to main.gd for input recording (#507)
 	pause_requested.emit()
@@ -311,14 +316,14 @@ func _end_player_conversation() -> void:
 			entry.timestamp_msec = now
 	_log_dirty = true
 
-	# D-069: Clear dialogue/confrontation dip
-	AudioManager.clear_dip()
+	# D-069: Clear dialogue/confrontation dip — coordinator routes to AudioManager
+	audio_dip_cleared.emit()
 
 	# D-061: unpause — signal to main.gd for input recording (#507)
 	unpause_requested.emit()
 
-	# D-064: unblock movement immediately — log entries stay visible but don't block input.
-	GameState.dialogue_active = false
+	# D-064: unblock movement immediately — coordinator handles GameState update.
+	dialogue_state_changed.emit(false)
 
 	# If no entries remain, hide the panel with fade.
 	if _log_entries.is_empty():
@@ -331,11 +336,11 @@ func hide_dialogue() -> void:
 		_end_player_conversation()
 		return  # _end_player_conversation may call hide_dialogue if log is empty
 
-	GameState.dialogue_active = false
+	dialogue_state_changed.emit(false)  # D-020: coordinator handles GameState update
 
 
 func is_dialogue_active() -> bool:
-	return _in_player_conversation or GameState.dialogue_active
+	return _in_player_conversation
 
 
 func has_active_entries() -> bool:
@@ -428,12 +433,12 @@ func _start_confrontation_beat(response_id: String, text: String) -> void:
 	_active_tween.tween_property(panel, "modulate:a", CONFRONTATION_DIM_ALPHA, 0.2)
 
 	confrontation_monologue.emit(UIStrings.get_text(CONFRONTATION_MONOLOGUE_KEY), CONFRONTATION_BEAT_DURATION)
-	AudioManager.apply_dip("confrontation")
+	audio_dip_requested.emit("confrontation")  # D-069: coordinator routes to AudioManager
 
 	_beat_tween = create_tween()
 	_beat_tween.tween_interval(CONFRONTATION_BEAT_DURATION)
 	_beat_tween.tween_callback(func():
-		AudioManager.clear_dip()
+		audio_dip_cleared.emit()  # D-069: coordinator routes to AudioManager
 		option_selected.emit(response_id, text)
 		_end_player_conversation()
 	)
@@ -443,7 +448,7 @@ func _cancel_beat() -> void:
 	if _beat_tween and _beat_tween.is_valid():
 		_beat_tween.kill()
 		_beat_tween = null
-		AudioManager.clear_dip()
+		audio_dip_cleared.emit()  # D-069: coordinator routes to AudioManager
 
 
 # -- Log rendering --