Support multi-repo hook management

[jasdumas]

Problem

install_hooks() works per-project. Developers with many repos need to install/update hooks across all of them, and organizations want consistent hook behavior.

Proposed Solution

• Add install_hooks_global() using git's core.hooksPath for global hook installation
• Add counselor_status() that scans common project directories for hook status
• Support a central config that applies to all repos
• Add update_hooks() for upgrading hook scripts when counselor updates

Example

# Install globally (all git repos get voice review)
counselor::install_hooks_global()

# Check all known projects
counselor::counselor_status()
# ~/projects/pkg1: ✓ hook installed (v0.2.0)
# ~/projects/pkg2: ✗ no hook
# ~/projects/pkg3: ⚠ outdated hook (v0.1.0)

Acceptance Criteria

• Global hook installation via core.hooksPath
• Status check across multiple repos
• Hook version tracking and update mechanism