refactor: section style keys live at style.container.section

style.container.section.font / .padding are the canonical paths for the
section styling (sections are container chrome, not a top-level style
domain); the old style.section spellings stay accepted as aliases, so
existing configs and stale binaries keep resolving. The global config.kdl
moves its section line under container { }.

Co-Authored-By: Claude Fable 5 <[email protected]>

 src/layout.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/layout.rs b/src/layout.rs
index d34e190..b23155e 100644
--- a/src/layout.rs
+++ b/src/layout.rs
@@ -75,7 +75,8 @@ fn flatten_json_to_flat_props(val: &serde_json::Value, prefix: &str, flat_props:
                 "style.control.textbox.corner_radius" | "style.textbox.corner_radius" | "style.data.textbox.corner_radius" => "textbox_corner_radius",
                 "style.control.dropdown.color" => "dropdown_color",
                 "style.control.font_selector.font" => "font_selector_font",
-                "style.section.font" => "section_label_font",
+                "style.container.section.font" | "style.section.font" => "section_label_font",
+                "style.container.section.padding" | "style.section.padding" => "section_padding",
                 "style.control.button_strip.font" => "button_strip_font",
                 "style.control.button_strip.spacing" => "button_strip_spacing",
                 "style.control.dropdown.height" => "dropdown_height",