Plugin hook scripts in cache lose execute permission on extraction (worktree / unknown hash path)

Description

Plugin hook shell scripts extracted into the plugin cache directory lose their execute permission (+x), causing Permission denied errors on every session stop. This appears to specifically affect git worktrees, where the cache path falls back to an unknown/ directory instead of a project-hash-based directory.

Steps to Reproduce

1. Install a plugin with a Stop hook (e.g., ralph-loop from claude-plugins-official)
2. Open Claude Code from a git worktree (not the main working tree)
3. Start a session, then let it stop normally

Expected Behavior

Hook runs successfully.

Actual Behavior

Stop hook error: Failed with non-blocking status code:
/bin/sh: /Users/user/.claude/plugins/marketplaces/claude-plugins-official/plugins/ralph-loop/hooks/stop-hook.sh: Permission denied

Root Cause

The plugin cache at ~/.claude/plugins/cache/ creates per-project copies of plugin files, keyed by a hash of the project path:

cache/claude-plugins-official/ralph-loop/8908a582f80d/hooks/stop-hook.sh  (-rwxr-xr-x)
cache/claude-plugins-official/ralph-loop/61c0597779bd/hooks/stop-hook.sh  (-rwxr-xr-x)
cache/claude-plugins-official/ralph-loop/unknown/hooks/stop-hook.sh       (-rw-r--r--) ← broken

For git worktrees, the hash computation apparently fails and falls back to unknown/. The file extracted into unknown/ is missing the execute bit. Running chmod +x fixes it temporarily, but the next session re-extracts the file and overwrites it without +x again.

The hash-based directories (8908a582f80d, etc.) have correct permissions — only unknown/ is affected.

Environment

• macOS (Darwin 25.2.0, arm64)
• Claude Code CLI
• Git worktrees at non-standard paths (e.g., ~/project-wt2/ alongside main ~/project/)

Suggested Fix

Either:

1. After extracting plugin files into the cache, chmod +x any .sh files in hooks/
2. Have the hook runner invoke shell scripts via bash <script> instead of executing them directly, which doesn't require +x
3. Fix the hash computation to handle worktree paths (resolve to the main repo's .git dir)