Show active project settings on session start

Summary

When starting a session in a project that has settings configured (e.g., sandbox enabled in .claude/settings.json), Claude Code should notify the user which settings are active.

Problem

Currently, there's no indication at session start that project-level settings are already applied. For example, if sandbox is enabled in .claude/settings.json, running /sandbox manually gives no feedback that it was already active — leading to redundant commands and confusion about whether settings are in effect.

Suggested Behavior

On session start, briefly surface active project settings, e.g.:

✓ Project settings loaded from .claude/settings.json
  - Sandbox: enabled (auto-allow bash)

Or at minimum, when a user runs a command like /sandbox that's already configured, notify them: "Sandbox is already enabled via project settings."

Context

• Settings file: .claude/settings.json in the project root
• Affects any project-level setting that a user might try to enable manually without realizing it's already active