feat(cli): TUI component architecture — status bars, message list, input bar

- Split monolithic app.tsx into composable components:
  - TopBar: connection indicator (●/○), gateway URL, model name, conversation ID
  - BottomBar: cwd, git branch, token usage
  - MessageList: timestamped messages, tool call indicators, thinking display
  - InputBar: context-aware prompt with streaming/disconnect states
- Extract socket logic into useSocket hook with typed events
- Extract git/cwd info into useGitInfo hook
- Quiet disconnect: single indicator instead of error flood
- Add @mosaic/types dependency for typed Socket.IO events
- Add PRD and task tracking docs

Tasks: TUI-001 through TUI-007 (Wave 1)

packages/cli/src/tui/components/input-bar.tsx

@@ -0,0 +1,44 @@
+import React, { useState, useCallback } from 'react';
+import { Box, Text } from 'ink';
+import TextInput from 'ink-text-input';
+
+export interface InputBarProps {
+  onSubmit: (value: string) => void;
+  isStreaming: boolean;
+  connected: boolean;
+}
+
+export function InputBar({ onSubmit, isStreaming, connected }: InputBarProps) {
+  const [input, setInput] = useState('');
+
+  const handleSubmit = useCallback(
+    (value: string) => {
+      if (!value.trim() || isStreaming || !connected) return;
+      onSubmit(value);
+      setInput('');
+    },
+    [onSubmit, isStreaming, connected],
+  );
+
+  const placeholder = !connected
+    ? 'disconnected — waiting for gateway…'
+    : isStreaming
+      ? 'waiting for response…'
+      : 'message mosaic…';
+
+  const promptColor = !connected ? 'red' : isStreaming ? 'yellow' : 'green';
+
+  return (
+    <Box paddingX={1} borderStyle="single" borderColor="gray">
+      <Text bold color={promptColor}>
+        ❯{' '}
+      </Text>
+      <TextInput
+        value={input}
+        onChange={setInput}
+        onSubmit={handleSubmit}
+        placeholder={placeholder}
+      />
+    </Box>
+  );
+}