SessionStart hook fails on Windows: CLAUDE_PLUGIN_ROOT path separators stripped

Bug Description

On Windows, SessionStart hooks fail because ${CLAUDE_PLUGIN_ROOT} path loses backslashes and colons when passed to bash, resulting in an invalid path.

Environment

• OS: Windows 11 Home 10.0.26200
• Shell: Git Bash
• Claude Code: Latest (CLI)
• Plugin: superpowers 4.3.0 (also affects learning-output-style, explanatory-output-style)

Error

From debug log (~/.claude/debug/*.txt):

Hook SessionStart:clear (SessionStart) error:
/bin/bash: C:Usersyohei.claudepluginscacheclaude-plugins-officialsuperpowers4.3.0/hooks/session-start.sh: No such file or directory

Expected Behavior

${CLAUDE_PLUGIN_ROOT} should resolve to a valid path like:

C:/Users/yohei/.claude/plugins/cache/claude-plugins-official/superpowers/4.3.0/hooks/session-start.sh

Actual Behavior

Path separators (\) and colon (:) are stripped, producing:

C:Usersyohei.claudepluginscacheclaude-plugins-officialsuperpowers4.3.0/hooks/session-start.sh

Reproduction

1. Install Claude Code CLI on Windows with Git Bash
2. Enable a plugin with SessionStart hooks (e.g., superpowers)
3. Start or resume a session
4. Observe "SessionStart:resume hook error" message
5. Check ~/.claude/debug/*.txt for the full error

Notes

• Running the hook script manually with a correctly set CLAUDE_PLUGIN_ROOT works fine
• The hook error appears on every session start/resume/clear but does not block functionality
• The issue is in how Claude Code expands ${CLAUDE_PLUGIN_ROOT} before passing the command to /bin/bash on Windows