Permission patterns with ~ paths don't match when paths are converted to relative

Bug Description

Permission patterns using ~ paths (e.g., Write(~/.claude/**)) don't work because the permission system converts absolute paths to relative paths before matching.

Steps to Reproduce

1. Add Write(~/.claude/**) to global settings.json permissions
2. From ~/.claude directory, attempt to write to ~/.claude/handoffs/test.md
3. Permission prompt appears asking for Write(handoffs/test.md)

Expected Behavior

Write(~/.claude/**) should match any write to files inside ~/.claude/, regardless of current working directory.

Actual Behavior

• The permission prompt shows a relative path: Write(handoffs/test.md)
• The pattern ~/.claude/** doesn't match handoffs/test.md because one is absolute-style and one is relative
• Even explicit Write(~/.claude/handoffs/**) doesn't match

Environment

• macOS
• Claude Code CLI
• Pattern tested in both global settings.json and slash command allowed-tools

Analysis

The permission system appears to:

1. Take the absolute path from the tool call (e.g., /Users/user/.claude/handoffs/test.md)
2. Convert it to relative (from cwd): handoffs/test.md
3. Match against patterns literally

This means ~/.claude/** can never match because the path being checked doesn't start with ~/.claude/.

Suggested Fix

Either:

1. Normalize both pattern and path to absolute before comparing
2. Expand ~ in patterns and compare against absolute paths
3. Don't convert paths to relative before matching

Workaround Attempted

• Write(~/.claude/**) - doesn't work
• Write(~/.claude/handoffs/**) - doesn't work
• Write(handoffs/**) - only works when cwd is ~/.claude
• Write(**/handoffs/**) - untested, may work but overly permissive