This commit addresses the accessibility issues described in Issue 296:
1. Replaced `pointerInput` gestures with `combinedClickable(role = Role.Button)` in `ChatBubble.kt` and `ChatScreen.kt` to ensure screen readers announce interactive text elements and chat bubbles correctly.
2. Added `role = Role.Button` to the clickable modifiers in `SessionsScreen.kt`.
3. Introduced proper `testTag` modifiers throughout interactive components like `session_card`, `chat_bubble_user`, `chat_bubble_assistant`, and `clarify_option` to facilitate UI testing.