fix(client): address PR #22 review — 3 critical bugs, 2 warnings, 8 suggestions

Critical fixes:
- fog_state: guard _compute_bounds() against all-invalid tiles (negative Rect2i crash)
- fog_shader: read Camera2D zoom dynamically instead of hardcoded Vector2(2,2)
- world_radial: set custom_minimum_size in _ready() from spoke geometry

Warnings:
- fog.gdshader: tighten PERIPHERAL_LOW 0.15→0.55 to match D-059 peripheral band
- Extract color_for_entity_kind() to Constants.gd, decouple CursorRenderer from EntityRenderer

Documentation: shallow copy assumption, gradual decay TODO, tween guard rationale,
fade timing rationale, ToggleInsert TODO, monologue consume-once, hover offset safety,
v6 fixture gap TODO.

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

client/scripts/main.gd

@@ -40,10 +40,12 @@ func _process(_delta: float) -> void:
 			stance_indicator.update_from_state()
 
 		# Show monologue if server sent one this tick (#414)
+		# Consume-once: set to null after showing to prevent re-display.
+		# Single monologue per snapshot is guaranteed by server.
 		if GameState.current_monologue != null and monologue_display:
 			var mono: Dictionary = GameState.current_monologue
 			monologue_display.show_monologue(mono.get("text", ""), mono.get("duration_seconds", 5.0))
-			GameState.current_monologue = null  # Consume — don't re-show next frame
+			GameState.current_monologue = null
 
 	# Track camera to player position every frame (D-015: locked, no panning)
 	# Camera2D smoothing handles interpolation — we just set the target