TUI chat input text renders with #eeeeee background in Hyper terminal

### Checks

- [x] I have searched [github.com/aws/amazon-q-developer-cli/issues](https://github.com/aws/amazon-q-developer-cli/issues?q=) and there are no duplicates of my issue
- [x] I have run `q doctor` in the affected terminal session
- [x] I have run `q restart` and replicated the issue again

### Operating system

macOS 26.2.0 (25C56)

### Expected behaviour

Input text background should be transparent or match the terminal/theme background color.

### Actual behaviour

After pressing Enter in kiro-cli --tui, the submitted input text displays with a visible light gray (#eeeeee) background box in Hyper terminal. The background should match the terminal/theme background.

Steps to reproduce:

1. Use Hyper terminal
2. Run kiro-cli --tui
3. Type any input and press Enter
4. Observe light gray (#eeeeee) background on the submitted text

Root cause investigation:

The kiro-cli-chat binary contains hardcoded light color palette values that appear to be applied regardless of the selected theme (currently set to dark):

bgColor: { truecolor: "#EEEEEE", color256: 255 }
surface: { truecolor: "#EEEEEE", color256: 255 }

These are in the base/light theme color definitions embedded in the binary.

### Steps to reproduce

After pressing Enter in kiro-cli --tui, the submitted input text displays with a visible light gray (#eeeeee) background box in Hyper terminal. The background should match the terminal/theme background.

Steps to reproduce:

1. Use Hyper terminal
2. Run kiro-cli --tui
3. Type any input and press Enter
4. Observe light gray (#eeeeee) background on the submitted text

### Environment

```yaml

[q-details]
version = "1.29.5"
hash = "65d65886c935861b3280015bea70bc617699c545"
date = "2026-04-07T03:42:50.041895Z (15h ago)"
variant = "full"

[system-info]
os = "macOS 26.2.0 (25C56)"
chip = "Apple M1 Max"
total-cores = 10
memory = "32.00 GB"

[environment]
cwd = "/Users/USER"
cli-path = "/Users/USER"
os = "Mac"
shell-path = "/bin/bash"
shell-version = "3.2.57"
terminal = "Hyper"
install-method = "brew"

[env-vars]
PATH = "/Users/USER/.pyenv/shims:/usr/local/bin:/Users/USER/Library/Java/JavaVirtualMachines/corretto-1.8.0_452/Contents/Home/bin:/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/opt/pmk/env/global/bin:/Users/USER/.local/bin"
QTERM_SESSION_ID = "85f1413d059e437c85d1f3d8a19177cc"
Q_SET_PARENT_CHECK = "1"
Q_TERM = "1.29.5"
SHELL = "/bin/zsh"
TERM = "xterm-256color"
__CFBundleIdentifier = "co.zeit.hyper"
```