feat: add "extension" linemode (m e) to show extensions of files

Solves sxyazi#903

yazi-config/preset/keymap.toml

@@ -88,6 +88,7 @@ keymap = [
 	{ on = [ "m", "s" ], run = "linemode size",        desc = "Set linemode to size" },
 	{ on = [ "m", "p" ], run = "linemode permissions", desc = "Set linemode to permissions" },
 	{ on = [ "m", "m" ], run = "linemode mtime",       desc = "Set linemode to mtime" },
+	{ on = [ "m", "m" ], run = "linemode extension",   desc = "Set linemode to extension" },
 	{ on = [ "m", "n" ], run = "linemode none",        desc = "Set linemode to none" },
 
 	# Copy

yazi-plugin/preset/components/folder.lua

@@ -21,6 +21,8 @@ function Folder:linemode(area, files)
 			spans[#spans + 1] = ui.Span(time and os.date("%y-%m-%d %H:%M", time // 1) or "")
 		elseif mode == "permissions" then
 			spans[#spans + 1] = ui.Span(f.cha:permissions() or "")
+		elseif mode == "extension" then
+			spans[#spans + 1] = ui.Span(f.url:extension() or "")
 		end
 
 		spans[#spans + 1] = ui.Span(" ")

yazi-plugin/src/url/url.rs

@@ -20,6 +20,9 @@ impl Url {
 			reg.add_method("stem", |lua, me, ()| {
 				me.file_stem().map(|s| lua.create_string(s.as_encoded_bytes())).transpose()
 			});
+			reg.add_method("extension", |lua, me, ()| {
+				me.extension().map(|s| lua.create_string(s.as_encoded_bytes())).transpose()
+			});
 			reg.add_method("join", |lua, me, other: UrlRef| Self::cast(lua, me.join(&*other)));
 			reg.add_method("parent", |lua, me, ()| {
 				me.parent_url().map(|u| Self::cast(lua, u)).transpose()