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.

packages/cli/src/ui/components/messages/ToolMessage.tsx

@@ -26,7 +26,6 @@ export const ToolMessage: React.FC<ToolMessageProps> = ({
   const statusIndicatorWidth = 3;
   const hasResult = resultDisplay && resultDisplay.toString().trim().length > 0;
   const staticHeight = /* Header */ 1;
-  availableTerminalHeight -= staticHeight;
 
   let displayableResult = resultDisplay;
   let hiddenLines = 0;
@@ -37,7 +36,7 @@ export const ToolMessage: React.FC<ToolMessageProps> = ({
     const lines = resultDisplay.split('\n');
     // Estimate available height for this specific tool message content area
     // This is a rough estimate; ideally, we'd have a more precise measurement.
-    const contentHeightEstimate = availableTerminalHeight - 5; // Subtracting lines for tool name, status, padding etc.
+    const contentHeightEstimate = availableTerminalHeight - staticHeight - 5; // Subtracting lines for tool name, status, padding etc.
     if (lines.length > contentHeightEstimate && contentHeightEstimate > 0) {
       displayableResult = lines.slice(0, contentHeightEstimate).join('\n');
       hiddenLines = lines.length - contentHeightEstimate;
@@ -83,7 +82,11 @@ export const ToolMessage: React.FC<ToolMessageProps> = ({
           <Box flexDirection="column">
             {typeof displayableResult === 'string' && (
               <Box flexDirection="column">
-                <MarkdownDisplay text={displayableResult} />
+                <MarkdownDisplay
+                  text={displayableResult}
+                  isPending={false}
+                  availableTerminalHeight={availableTerminalHeight}
+                />
               </Box>
             )}
             {typeof displayableResult === 'object' && (