Fix non-square consent checkbox with a dedicated Panel square

Root cause: CheckBox/Button reserves vertical space for a text
baseline even with an empty string, so no amount of custom_minimum_size
or stylebox content-margin tweaking produced a true square - it just
came out close-but-not-quite in some layouts and visibly elongated in
others.

Decoupled the visual square from the CheckBox entirely: a plain Panel
(exactly 20x20, toggled by direct click) now draws the border/fill,
while a real (invisible) CheckBox still holds .button_pressed for the
rest of the code to read. Also added left padding on the row and
vertically centered both the square and the consent text within it.

Verified with a direct size dump (20x20 in both checked/unchecked
states, where it previously measured non-square) and rendered
screenshots of both states.

scripts/ui/login_screen.gd

@@ -27,6 +27,7 @@ var login_input: LineEdit
 var password_input: LineEdit
 var password_reveal_entries: Array[Dictionary] = []
 var legal_consent_texts: Array[RichTextLabel] = []
+var legal_consent_squares: Array[Panel] = []
 var registration_username_input: LineEdit
 var registration_email_input: LineEdit
 var registration_password_input: LineEdit
@@ -351,25 +352,47 @@ func _add_legal_consent(parent: VBoxContainer) -> CheckBox:
 	# wrapping then stays confined to its column, and "Terms of Service"/
 	# "Privacy Policy" render as inline links rather than a duplicate row
 	# of link buttons underneath.
+	#
+	# The actual toggle state lives on a real CheckBox (kept invisible and
+	# out of the row's layout) because other code reads .button_pressed -
+	# but Button/CheckBox reserves vertical space for a text baseline even
+	# with an empty string, which was making the visible square non-square
+	# no matter what custom_minimum_size said. Drawing the visible square
+	# as a plain Panel sidesteps that entirely.
+	var check := CheckBox.new()
+	check.visible = false
+	parent.add_child(check)
+
 	var margin := MarginContainer.new()
+	margin.add_theme_constant_override("margin_left", 6)
 	margin.add_theme_constant_override("margin_top", 8)
 	margin.add_theme_constant_override("margin_bottom", 8)
 	parent.add_child(margin)
 	var row := HBoxContainer.new()
 	row.add_theme_constant_override("separation", 12)
 	margin.add_child(row)
-	var check := CheckBox.new()
+
-	check.name = "LegalConsentCheckBox"
+	var square := Panel.new()
-	check.custom_minimum_size = Vector2(22, 22)
+	square.custom_minimum_size = Vector2(20, 20)
-	check.size_flags_vertical = Control.SIZE_SHRINK_BEGIN
+	square.size_flags_horizontal = Control.SIZE_SHRINK_BEGIN
-	check.add_theme_icon_override("unchecked", _blank_icon())
+	square.size_flags_vertical = Control.SIZE_SHRINK_CENTER
-	row.add_child(check)
+	square.mouse_filter = Control.MOUSE_FILTER_STOP
+	square.set_meta("legal_consent_checkbox", check)
+	square.gui_input.connect(func(event: InputEvent):
+		if event is InputEventMouseButton and event.pressed and event.button_index == MOUSE_BUTTON_LEFT:
+			check.button_pressed = not check.button_pressed
+	)
+	row.add_child(square)
+	legal_consent_squares.append(square)
+	check.toggled.connect(func(_pressed: bool): _refresh_legal_consent_square(square))
+
 	var consent_text := RichTextLabel.new()
 	consent_text.bbcode_enabled = true
 	consent_text.fit_content = true
 	consent_text.scroll_active = false
 	consent_text.meta_underlined = false
 	consent_text.size_flags_horizontal = Control.SIZE_EXPAND_FILL
+	consent_text.size_flags_vertical = Control.SIZE_SHRINK_CENTER
 	consent_text.add_theme_font_override("normal_font", Brand.font)
 	consent_text.add_theme_font_size_override("normal_font_size", 13)
 	consent_text.meta_clicked.connect(func(meta: Variant): _open_legal_document(str(meta)))
@@ -378,10 +401,6 @@ func _add_legal_consent(parent: VBoxContainer) -> CheckBox:
 	return check
 
 
-func _blank_icon() -> ImageTexture:
-	return ImageTexture.create_from_image(Image.create(1, 1, false, Image.FORMAT_RGBA8))
-
-
 func _refresh_legal_consent_text(consent_text: RichTextLabel, dark: bool) -> void:
 	var text_hex := Brand.text_color(dark).to_html(false)
 	var link_hex := (Brand.SKY_BLUE if dark else Brand.ROYAL_BLUE).to_html(false)
@@ -391,6 +410,19 @@ func _refresh_legal_consent_text(consent_text: RichTextLabel, dark: bool) -> voi
 	)
 
 
+func _refresh_legal_consent_square(square: Panel) -> void:
+	var dark := UIThemeService.is_dark_mode()
+	var accent := Brand.SKY_BLUE if dark else Brand.ROYAL_BLUE
+	var checked := square.get_meta("legal_consent_checkbox", null) as CheckBox
+	var is_checked := checked != null and checked.button_pressed
+	var box := StyleBoxFlat.new()
+	box.bg_color = accent if is_checked else Color.TRANSPARENT
+	box.border_color = accent
+	box.set_border_width_all(2)
+	box.set_corner_radius_all(5)
+	square.add_theme_stylebox_override("panel", box)
+
+
 func _add_legal_links(parent: HBoxContainer) -> void:
 	for spec in [["Terms of Service", "terms"], ["Privacy Policy", "privacy"]]:
 		var link := Button.new()
@@ -597,15 +629,8 @@ func _apply_theme() -> void:
 		_style_auth_field(input, dark)
 	for consent_text in legal_consent_texts:
 		_refresh_legal_consent_text(consent_text, dark)
-	var checkbox_box := StyleBoxFlat.new()
+	for square in legal_consent_squares:
-	checkbox_box.bg_color = Color.TRANSPARENT
+		_refresh_legal_consent_square(square)
-	checkbox_box.border_color = Brand.SKY_BLUE if dark else Brand.ROYAL_BLUE
-	checkbox_box.set_border_width_all(2)
-	checkbox_box.set_corner_radius_all(6)
-	checkbox_box.set_content_margin_all(0)
-	for cb in find_children("*", "CheckBox", true, false):
-		for state in ["normal", "hover", "pressed", "focus"]:
-			cb.add_theme_stylebox_override(state, checkbox_box)
 	for button in find_children("*", "Button", true, false):
 		if button is CheckBox:
 			continue