Plan mode doesn't deactivate bypass permissions mode

Description

When switching from bypass permissions mode to plan mode (via Shift+Tab), bypass permissions stays active. Plan mode restrictions don't take effect — Claude continues to execute tools without prompting.

Expected behavior

Entering plan mode should deactivate bypass permissions, since they are conceptually incompatible:

• Plan mode = "research and propose, don't execute changes"
• Bypass permissions = "execute everything without asking"

These are mutually exclusive intents. If I switch to plan mode, I expect the "don't execute" contract to be enforced regardless of the prior permission mode.

Steps to reproduce

1. Start Claude Code with --dangerously-skip-permissions or enter bypass permissions mode
2. Press Shift+Tab to cycle to plan mode
3. Observe that Claude still executes tools without permission prompts (bypass behavior persists)

Environment

• Claude Code CLI (latest)
• macOS Darwin 25.3.0