refactor: convert mac-optimizer from raw skill to proper plugin

Restructured 92-mac-optimizer from a CLAUDE.md-based skill into a full
Claude Code plugin with .claude-plugin/plugin.json, 6 slash commands
(/mac-doctor, /mac-packages, /mac-environment, /mac-security,
/mac-cleanup, /mac-resources), and auto-trigger SKILL.md.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

custom-skills/92-mac-optimizer/.claude-plugin/plugin.json

@@ -0,0 +1,45 @@
+{
+  "name": "mac-optimizer",
+  "version": "1.0.0",
+  "description": "Modular macOS system health toolkit with read-only audits, cleanup, and security checks",
+  "author": {
+    "name": "OurDigital"
+  },
+  "keywords": [
+    "macos",
+    "system",
+    "optimization",
+    "cleanup",
+    "security",
+    "homebrew",
+    "packages",
+    "disk-space"
+  ],
+  "license": "MIT",
+  "commands": [
+    {
+      "name": "mac-doctor",
+      "description": "Full macOS system health check — runs all 5 audit modules and presents unified findings"
+    },
+    {
+      "name": "mac-packages",
+      "description": "Audit package managers (Homebrew, npm, pip, pyenv) for outdated packages and issues"
+    },
+    {
+      "name": "mac-environment",
+      "description": "Audit shell environment — PATH, symlinks, shell configs, and startup time"
+    },
+    {
+      "name": "mac-security",
+      "description": "Security posture assessment — SIP, Gatekeeper, Firewall, FileVault, SSH, ports"
+    },
+    {
+      "name": "mac-cleanup",
+      "description": "Scan and clean caches, logs, and clutter — shows sizes first, cleans only with consent"
+    },
+    {
+      "name": "mac-resources",
+      "description": "Monitor CPU, memory, disk, battery, and identify resource-hungry processes"
+    }
+  ]
+}