Refactor chat component styles for responsiveness and consistency

- Updated padding and margin properties across various chat components to utilize responsive design tokens, ensuring better adaptability to different screen sizes.
- Replaced fixed sizes with responsive variables for buttons, avatars, and bubbles to enhance UI flexibility.
- Adjusted font sizes to use responsive tokens, improving text readability on various devices.
- Standardized border-radius and other dimensions using CSS variables for a cohesive design language.
- Enhanced dialog and screen components with safe area insets for better compatibility with modern devices.

src/app/subscription/components/subscription-screen.module.css

@@ -1,7 +1,7 @@
 .shell {
   display: flex;
   flex-direction: column;
-  min-height: 100dvh;
+  min-height: var(--app-viewport-height, 100dvh);
   background:
     radial-gradient(circle at 8% 4%, rgba(255, 255, 255, 0.95) 0 90px, transparent 160px),
     linear-gradient(180deg, #fff9fb 0%, #fcf3f4 52%, #fffefe 100%);