[Bug] Interactive TUI elements (Permissions, Slash commands) leave ghost visual artifacts and break scroll/rendering in iTerm2

### Environment
- **CLI Tool:** `agy` (Antigravity CLI)
- **Version:** `1.0.1`
- **OS:** macOS 15.7 (Sequoia)
- **Terminal Emulator:** iTerm2
- **Shell:** `zsh`
- **Terminal size:** Typically ~80 columns x 24 lines (reproducible across various sizes)

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### Description of the Bug
There are severe Terminal User Interface (TUI) rendering and redraw issues in `agy` version `1.0.1` that make interactive sessions extremely difficult and confusing to use. These rendering glitches occur across three primary scenarios:

#### Scenario 1: Permission Prompt Buttons Don't Clear (Ghost Buttons)
When the agent prompts for tool execution permissions (e.g., displaying `[Yes] [No] [For this session] [Always]`), making a selection and pressing Enter commits the action but **fails to erase or clean up the choice buttons from the terminal screen**.
- **The Glitch:** The interactive menu buttons remain drawn permanently in the terminal buffer.
- **The Impact:** The user is left unsure of the agent's current state. Even worse, if the user scrolls or tries to use keyboard arrows (Up/Down) afterwards, the text overlaps with the stale menu drawings, showing duplicated text chunks and breaking command line cursor movements.

#### Scenario 2: Slash Command Overlay GUI Does Not Exit Gracefully
When executing a slash command that displays an interactive layout (such as `/usage` or `/help` visual overlay screen), exiting the layout by pressing `Esc` closes the command loop, but **does not clear the interactive overlay graphics from the screen buffer**. The layout persists as a static "ghost drawing," cluttering the active terminal prompt area.

#### Scenario 3: `Ctrl + L` Wipes Chat History, Requiring Window Resize to Redraw
To clear the cluttered/stale screen buffer, users naturally attempt to use `Ctrl + L` (clear screen).
- **The Glitch:** Pressing `Ctrl + L` completely wipes out the entire visible active chat history, leaving a blank canvas.
- **The Workaround:** The only way to force `agy` to redraw the conversation history and bring back the interface text is by manually resizing (maximizing/minimizing or dragging to resize) the iTerm2 window.

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### Steps to Reproduce
1. Start an interactive session: `agy -i`
2. Trigger any tool command that requests permissions. Select `Yes` (or another option) and press `Enter`. Observe that the options box is never cleared from the screen.
3. Type a slash command that draws a fullscreen or overlay screen (e.g. `/usage`). Press `Esc` to exit. Observe that the drawn overlay graphics remain printed on top of the active shell feed.
4. Try using Up/Down arrow keys or typing. Observe messy duplicate texts.
5. Press `Ctrl + L`. The chat disappears entirely. Resize the window to force it to redraw.

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### Expected Behavior
1. Upon committing a choice (like tool permissions), the CLI should cleanly clear the ANSI lines of the prompt selection interface, leaving only the executed command or a clean state.
2. Exiting interactive slash command layouts (`Esc`) should cleanly restore the previous terminal screen buffer or completely wipe the overlay drawing.
3. `Ctrl + L` should trigger a full refresh/redraw of the active chat interface in the terminal buffer instead of wiping the history blank, or at least respect the shell's default scrollback behavior without breaking the TUI.