Refactor: Improve UI rendering and address code review comments

This commit addresses several code review comments primarily focused on improving the rendering and stability of the CLI UI.

Key changes include:
- Passing `isPending` and `availableTerminalHeight` props to `MarkdownDisplay` to enable more intelligent rendering of content, especially for pending messages and code blocks.
- Adjusting height calculations in `ToolGroupMessage` and `ToolMessage` to more accurately reflect available space.
- Refining the logic in `App.tsx` for measuring and utilizing terminal height, including renaming `footerRef` to `mainControlsRef` for clarity.
- Ensuring consistent prop drilling for `isPending` and `availableTerminalHeight` through `HistoryItemDisplay`, `GeminiMessage`, and `GeminiMessageContent`.
- In `MarkdownDisplay`, when `isPending` is true and content exceeds `availableTerminalHeight`, the code block will now be truncated with a "... generating more ..." message. If there's insufficient space even for the
message, a simpler "... code is being written ..." will be shown.

1 files changed, 12 insertions, 2 deletions

diff --git a/packages/cli/src/ui/components/messages/GeminiMessage.tsx b/packages/cli/src/ui/components/messages/GeminiMessage.tsx
index b2c816a9..df8d0a87 100644
--- a/packages/cli/src/ui/components/messages/GeminiMessage.tsx
+++ b/packages/cli/src/ui/components/messages/GeminiMessage.tsx
@@ -11,9 +11,15 @@ import { Colors } from '../../colors.js';
 
 interface GeminiMessageProps {
   text: string;
+  isPending: boolean;
+  availableTerminalHeight: number;
 }
 
-export const GeminiMessage: React.FC<GeminiMessageProps> = ({ text }) => {
+export const GeminiMessage: React.FC<GeminiMessageProps> = ({
+  text,
+  isPending,
+  availableTerminalHeight,
+}) => {
   const prefix = '✦ ';
   const prefixWidth = prefix.length;
 
@@ -23,7 +29,11 @@ export const GeminiMessage: React.FC<GeminiMessageProps> = ({ text }) => {
         <Text color={Colors.AccentPurple}>{prefix}</Text>
       </Box>
       <Box flexGrow={1} flexDirection="column">
-        <MarkdownDisplay text={text} />
+        <MarkdownDisplay
+          text={text}
+          isPending={isPending}
+          availableTerminalHeight={availableTerminalHeight}
+        />
       </Box>
     </Box>
   );