fix(yarn): use corepack/npm instead of apt, prevent cmdtest conflict

Problem: yarn update tried to use apt and installed wrong package
- catalog used install_method: "package_manager" with apt: "yarnpkg"
- Ubuntu's "yarn" package is actually "cmdtest" (naming conflict!)
- Installed cmdtest (Python testing tool) instead of yarn
- yarn 1.22.22 (nvm) wasn't updated to 4.10.3
- Wrong approach: should use corepack/npm, not apt

Root cause: apt yarn package naming conflict
- Debian/Ubuntu: package "yarn" → cmdtest (legacy)
- Debian/Ubuntu: package "yarnpkg" → yarn (workaround)
- But catalog said "yarnpkg" and apt installed "cmdtest" anyway

Solution: Use dedicated installer with corepack/npm

Changes:
- catalog/yarn.json: Changed to dedicated_script method
- scripts/install_yarn.sh: New installer using corepack/npm
  - Checks if Node.js is nvm-managed (like gem checks rbenv)
  - Updates via: corepack prepare yarn@stable --activate
  - Fallback: npm install -g yarn@latest
  - Removes cmdtest if present (apt conflict cleanup)

Expected workflow:
1. Ensure Node.js is nvm-managed (scripts/install_node.sh reconcile)
2. Update yarn via corepack: scripts/install_yarn.sh update
3. Falls back to npm if corepack unavailable

Manual cleanup required:
  sudo apt remove cmdtest python3-cliapp python3-ttystatus python3-zombie-imp

Note: Order in guide.sh:
- Node.js: order 40
- npm: order 141
- pnpm: order 142
- yarn: order 151 (processes after Node.js/npm)

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

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

Author: AI Assistant

catalog/yarn.json

@@ -1,14 +1,14 @@
 {
   "name": "yarn",
-  "install_method": "package_manager",
+  "install_method": "dedicated_script",
   "description": "Alternative Node.js package manager with offline mode and deterministic installs",
   "homepage": "https://yarnpkg.com/",
   "binary_name": "yarn",
-  "packages": {
-    "apt": "yarnpkg",
-    "brew": "yarn",
-    "dnf": "yarnpkg",
-    "pacman": "yarn"
-  },
-  "notes": "Can also be installed via npm: npm install -g yarn. Some distros use 'yarnpkg' package name to avoid conflicts."
+  "script": "install_yarn.sh",
+  "notes": "Installed via Node.js corepack or npm. Requires Node.js to be installed via nvm. Do NOT install via apt (conflicts with cmdtest package)."
+  ,"guide": {
+    "display_name": "Yarn",
+    "install_action": "update",
+    "order": 151
+  }
 }

scripts/install_yarn.sh

@@ -0,0 +1,102 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+. "$DIR/lib/common.sh"
+
+ACTION="${1:-update}"
+
+check_nvm_node() {
+  # Check if Node.js is nvm-managed
+  local node_path
+  node_path="$(command -v node 2>/dev/null || echo '')"
+
+  case "$node_path" in
+    "$HOME/.nvm/"*)
+      return 0  # nvm-managed
+      ;;
+    *)
+      return 1  # not nvm-managed (apt, system, or missing)
+      ;;
+  esac
+}
+
+update_yarn() {
+  ensure_nvm_loaded
+
+  if ! command -v node >/dev/null 2>&1; then
+    echo "[yarn] Error: Node.js not found. Install Node.js first via 'make install-node' or 'scripts/install_node.sh'" >&2
+    return 1
+  fi
+
+  # Check if Node.js is nvm-managed before trying to update yarn
+  if ! check_nvm_node; then
+    echo "[yarn] Error: Node.js is not nvm-managed (currently apt/system)" >&2
+    echo "[yarn] Cannot update yarn for system Node.js" >&2
+    echo "[yarn] Please install Node.js via nvm first:" >&2
+    echo "[yarn]   make install-node" >&2
+    echo "[yarn]   or: scripts/install_node.sh reconcile" >&2
+    return 1
+  fi
+
+  local before after path
+  before="$(yarn --version 2>/dev/null || echo '<none>')"
+
+  # Try corepack first (modern approach)
+  if command -v corepack >/dev/null 2>&1; then
+    echo "[yarn] Updating yarn via corepack..." >&2
+    corepack enable || true
+    corepack prepare yarn@stable --activate || true
+  else
+    # Fallback to npm global install
+    echo "[yarn] Updating yarn via npm..." >&2
+    npm install -g yarn@latest || true
+  fi
+
+  after="$(yarn --version 2>/dev/null || echo '<none>')"
+  path="$(command -v yarn 2>/dev/null || echo '<none>')"
+
+  printf "[%s] before: %s\n" "yarn" "$before"
+  printf "[%s] after:  %s\n" "yarn" "$after"
+  printf "[%s] path:   %s\n" "yarn" "$path"
+}
+
+install_yarn() {
+  echo "[yarn] yarn should be installed via Node.js corepack/npm. Installing/updating Node.js first..."
+  "$DIR/install_node.sh" install || true
+  update_yarn
+}
+
+reconcile_yarn() {
+  ensure_nvm_loaded
+
+  if ! command -v node >/dev/null 2>&1; then
+    echo "[yarn] Node.js not found. Installing Node.js (which includes yarn via corepack)..."
+    "$DIR/install_node.sh" reconcile || true
+  elif ! check_nvm_node; then
+    echo "[yarn] Node.js is not nvm-managed. Installing Node.js via nvm first..."
+    "$DIR/install_node.sh" reconcile || true
+  fi
+
+  # Remove apt-installed cmdtest if present (Ubuntu's yarn package conflict)
+  if command -v dpkg >/dev/null 2>&1 && dpkg -l | grep -q "^ii.*cmdtest"; then
+    echo "[yarn] Removing apt package 'cmdtest' (conflicts with yarn)..." >&2
+    apt_remove_if_present cmdtest yarnpkg || true
+  fi
+
+  update_yarn
+}
+
+uninstall_yarn() {
+  echo "[yarn] yarn is managed by Node.js/npm. To remove:" >&2
+  echo "[yarn]   npm uninstall -g yarn" >&2
+  echo "[yarn]   or: corepack disable" >&2
+}
+
+case "$ACTION" in
+  install) install_yarn ;;
+  update) update_yarn ;;
+  uninstall) uninstall_yarn ;;
+  reconcile) reconcile_yarn ;;
+  *) echo "Usage: $0 {install|update|uninstall|reconcile}" ; exit 2 ;;
+esac