feat(twenty-front): generalize the page primary/secondary bars (flat redesign) (#21308)

Replaces #21279 and #21282 with one clean PR from `main`.

Generalizes the settings primary-bar / secondary-bar card chrome to the
record index, record show and standalone pages via a shared
`PageCardLayout` + `PageCardHeader` (the side panel sits as a sibling of
the content card), and applies the new flat design direction: square
corners on the card, side panel and loading skeletons.

Iterating toward the new design (Figma node 102282-221623); the
confirmed direction and the explicit "remove rounded corners" change are
in, remaining designer specifics to follow.

packages/twenty-front/src/modules/command-menu/components/CommandMenuButton.tsx

@@ -28,6 +28,7 @@ export type CommandMenuButtonProps = {
   onClick?: (event?: MouseEvent<HTMLElement>) => void;
   to?: string;
   disabled?: boolean;
+  isPrimaryAction?: boolean;
 };
 
 export const CommandMenuButton = ({
@@ -35,6 +36,7 @@ export const CommandMenuButton = ({
   onClick,
   to,
   disabled = false,
+  isPrimaryAction = false,
 }: CommandMenuButtonProps) => {
   const resolvedLabel = getCommandMenuItemLabel(command.label);
 
@@ -50,8 +52,8 @@ export const CommandMenuButton = ({
         <Button
           Icon={command.Icon}
           size="small"
-          variant="secondary"
-          accent={buttonAccent}
+          variant={isPrimaryAction ? 'primary' : 'secondary'}
+          accent={isPrimaryAction ? 'blue' : buttonAccent}
           to={to}
           onClick={onClick}
           disabled={disabled}
@@ -63,8 +65,8 @@ export const CommandMenuButton = ({
           <IconButton
             Icon={command.Icon}
             size="small"
-            variant="secondary"
-            accent={buttonAccent}
+            variant={isPrimaryAction ? 'primary' : 'secondary'}
+            accent={isPrimaryAction ? 'blue' : buttonAccent}
             to={to}
             onClick={onClick}
             disabled={disabled}