fix(client): correct 5 bugs found in pre-PR review

- sound_indicator_renderer: draw_colored_polygon → draw_polygon (runtime crash)
- sound_indicator_renderer: append+dedup instead of clear — indicators now
  survive 3.5s instead of dying after one server tick
- dialogue_box: wire Constants.DIALOGUE_MAX_WIDTH (640px) instead of
  hardcoded 832px MAX_WIDTH_PX
- dialogue_box.tscn: update default offsets to ±320 (was ±416)
- decisions/perception.md: fix footer typo (1920px → 640px)
- tests updated for new append/dedup indicator behavior

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

client/ui/dialogue_box.tscn

@@ -20,9 +20,9 @@ anchor_left = 0.5
 anchor_top = 1.0
 anchor_right = 0.5
 anchor_bottom = 1.0
-offset_left = -416.0
+offset_left = -320.0
 offset_top = -200.0
-offset_right = 416.0
+offset_right = 320.0
 grow_horizontal = 2
 grow_vertical = 0