Thai combining characters (vowels/tones) missing/stripped when typing interactively in agy CLI inside Antigravity │ IDE terminal (Windows)

### What happened?

### Describe the Bug
When using the `agy` (Gemini CLI) tool interactively inside the integrated terminal of Antigravity IDE (TooCode),
Thai combining characters (like vowels and tone marks, e.g., ่, ี) are missing or stripped out as we type. For example,
typing "ไม่มี" (Mai-Mee) displays as "ไมม" (the vowels/tones are omitted).

This issue is highly specific to the combination of `agy` + Antigravity IDE Terminal.

### Diagnostics and Findings
1. **Normal Command Rendering is fine:** Running standard commands like `echo ไม่มี` inside the Antigravity IDE
terminal renders the Thai vowels and tone marks correctly.
2. **External Terminals are fine:** Running `agy` in external terminals (Windows Terminal, standard Cmd, standard
PowerShell, or standard VS Code) displays "ไม่มี" correctly during input typing.
3. **Environment details:**
- OS: Windows 10/11 (x64)
- Code Page: UTF-8 (Active code page: 65001)
- CLI Path: `C:\Users\Thear\AppData\Local\agy\bin\agy.exe`
- IDE `TERM_PROGRAM_VERSION`: 1.107.0

### Suspected Root Cause
The Node.js/Electron runtime packaged inside the Antigravity IDE (TooCode) seems to have an older TTY TTY-raw-mode
implementation on Windows. When interactive CLI prompts (like `agy` via readline/ink) put the terminal in raw mode
to read keypresses, combining characters or multi-byte Thai character input events are dropped or miscalculated.

### Expected Behavior
Typed Thai combining characters should be registered and rendered correctly in the CLI prompt inside the IDE,
matching the behavior of standard VS Code and external terminals.

### What did you expect to happen?

For example,
typing "ไม่มี" (Mai-Mee) displays as "ไมม" (the vowels/tones are omitted).

### Client information

Client Information

Run `gemini` to enter the interactive CLI, then run the `/about` command.

```console
> /about
# paste output here
```

### Login information

_No response_

### Anything else we need to know?

_No response_

Start by reproducing the agy interactive prompt in Antigravity's integrated terminal and compare typing with Windows Terminal, Cmd, PowerShell, and VS Code. Inspect the readline/ink raw-mode input path on Windows, then verify that Thai combining characters such as ่ and ี are retained and rendered in the prompt.

Written by the indexing model from the issue text.