fix(client): address PR #25 review — 5 critical bugs, 4 warnings, 3 suggestions

Critical fixes:
- hide_dialogue() sent PAUSE instead of UNPAUSE, permanently freezing
  simulation after every dialogue (both reviewers)
- Confrontation monologue hardcoded in GDScript constant, violating
  D-042/D-020 — moved to ui-strings.yaml as dialogue.confrontation_beat
- Walk-away WASD didn't call set_input_as_handled(), letting movement
  event propagate and potentially stepping on the same frame
- is_dialogue_active() returned _is_showing only — interaction list
  could flash during 300ms fade gap. Now includes dialogue_active state
- Removed dead _last_dialogue_id / get_dialogue_id() state (never read)

Warnings addressed:
- Audio registry now scans res://audio/ recursively (subdirs registered)
- add_bus_effect guarded against duplicate calls in tests
- int64 encoder dead code tagged KNOWN-DEFECT, filed as ticket #516
- D-073 zone crossfade stub comment clarifies Sprint 9+ deferral
- listening_focus dip documents caller tick-gate responsibility (D-069/D-071)

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

client/ui/dialogue_box.gd

@@ -23,7 +23,6 @@ var _option_response_ids: Array[String] = []  # response_id per option, same ind
 var _option_texts: Array[String] = []  # raw display text per option
 var _option_is_confrontation: Array[bool] = []  # confrontation flag per option
 var _npc_name: String = ""
-var _dialogue_id: int = 0  # Tracks current dialogue to prevent consume-once race
 
 const FADE_IN: float = 0.2
 const FADE_OUT: float = 0.3  # D-064: 300ms fade on walk-away
@@ -32,7 +31,7 @@ const MAX_HEIGHT_RATIO: float = 0.2   # D-061: max 20% viewport height
 const MAX_WIDTH_PX: float = 832.0     # D-061: max-width cap (~65% of 1280)
 const CONFRONTATION_BEAT_DURATION: float = 1.5  # D-063: pause before sending
 const CONFRONTATION_DIM_ALPHA: float = 0.7  # D-063: dialogue box dims during beat
-const CONFRONTATION_MONOLOGUE: String = "This changes things. No taking it back."
+const CONFRONTATION_MONOLOGUE_KEY: String = "dialogue.confrontation_beat"
 
 # D-064: movement actions that trigger walk-away
 const _WALK_AWAY_ACTIONS: Array[StringName] = [
@@ -58,6 +57,7 @@ func _unhandled_input(event: InputEvent) -> void:
 	if event is InputEventKey and event.pressed:
 		for action in _WALK_AWAY_ACTIONS:
 			if event.is_action_pressed(action):
+				get_viewport().set_input_as_handled()
 				_cancel_beat()
 				hide_dialogue()
 				dialogue_dismissed.emit()
@@ -82,7 +82,6 @@ func _update_layout() -> void:
 #          D-063: confrontation options render italic.
 func show_dialogue(npc_name: String, speech: String, options: Array = []) -> void:
 	_npc_name = npc_name
-	_dialogue_id += 1
 	_cancel_beat()
 
 	# NPC speech — name prefix in bold
@@ -158,7 +157,7 @@ func hide_dialogue() -> void:
 	mouse_filter = Control.MOUSE_FILTER_IGNORE
 
 	# D-061: unpause when dialogue closes
-	SimBridge.send_input({"action": InputMapper.Action.PAUSE, "timestamp_msec": Time.get_ticks_msec()})
+	SimBridge.send_input({"action": InputMapper.Action.UNPAUSE, "timestamp_msec": Time.get_ticks_msec()})
 
 	if _active_tween and _active_tween.is_valid():
 		_active_tween.kill()
@@ -172,11 +171,7 @@ func hide_dialogue() -> void:
 
 
 func is_dialogue_active() -> bool:
-	return _is_showing
-
-
-func get_dialogue_id() -> int:
-	return _dialogue_id
+	return _is_showing or GameState.dialogue_active
 
 
 func _on_option_pressed(index: int) -> void:
@@ -209,8 +204,8 @@ func _start_confrontation_beat(response_id: String, text: String) -> void:
 	_active_tween = create_tween()
 	_active_tween.tween_property(panel, "modulate:a", CONFRONTATION_DIM_ALPHA, 0.2)
 
-	# D-063: monologue beat — hardcoded v0.1 line
-	confrontation_monologue.emit(CONFRONTATION_MONOLOGUE, CONFRONTATION_BEAT_DURATION)
+	# D-063: monologue beat — text from ui-strings.yaml (D-042)
+	confrontation_monologue.emit(UIStrings.get_text(CONFRONTATION_MONOLOGUE_KEY), CONFRONTATION_BEAT_DURATION)
 
 	# D-063: audio dip via AudioManager
 	AudioManager.apply_dip("confrontation")