fix(catalog): switch pnpm to auto installation method

Changed pnpm from package_manager to auto method with npm_package
support to fix incorrect apt-based upgrade attempts for npm-installed
pnpm.

Before: install_method: "package_manager" (defaulted to apt)
After: install_method: "auto" with npm_package: "pnpm"

This enables the reconciliation system to detect npm installation
and use the correct update method (npm install -g pnpm).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: CybotTM

catalog/pnpm.json

@@ -1,14 +1,15 @@
 {
   "name": "pnpm",
-  "install_method": "package_manager",
+  "install_method": "auto",
   "description": "Fast, disk space efficient Node.js package manager",
   "homepage": "https://pnpm.io/",
+  "npm_package": "pnpm",
   "binary_name": "pnpm",
   "packages": {
     "apt": "pnpm",
     "brew": "pnpm",
     "dnf": "pnpm",
     "pacman": "pnpm"
   },
-  "notes": "Can also be installed via npm: npm install -g pnpm"
+  "notes": "Can be installed via npm (npm install -g pnpm), apt, or brew"
 }