[BUG] Cursor disappears when the `CI` environment variable is present but set to `false` / `NO` / `0`

Environment

• Platform (select one):
• [x] Anthropic API
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• [ ] Other: <!-- specify -->
• Claude CLI version: 1.0.43 (Claude Code)
• Operating System: macOS 15.5
• Terminal: iTerm2

Bug Description

When the CI environment variable exists—even with a falsey value (false, NO, or 0)—the Claude Code CLI starts in CI mode, leaving the terminal cursor hidden.

Steps to Reproduce

# Any of these three commands reproduces the issue
CI=false pnpm exec -- claude
CI=NO    pnpm exec -- claude
CI=0     pnpm exec -- claude

Expected Behavior

CI=false, CI=NO and CI=0 is treated as non CI mode.

Actual Behavior

The CLI treats CI=false, CI=no, and CI=0 the same as CI=true; it enters CI mode and the cursor remains hidden.

Additional Context

• Initial investigation suggests the issue may originate in Ink or in its CI-detection helpers (is-ci or is-in-ci).