chore(marketplace): add ourdigital-skills local marketplace + fix README install docs

Add .claude-plugin/marketplace.json: the ourdigital-skills local directory marketplace — 11 plugins. 8 themed skill plugins (core/seo/notion/jamie/notebooklm/gtm/dintel/utils) bundle 66 skills via custom-skills/NN-*/ roots; 3 standalone plugins (mac-optimizer, multi-agent-guide, dintel-bootstrap) expose their own commands/ + skills/. Whole manifest passes 'claude plugin validate'.

Fix mac-optimizer + multi-agent-guide plugin.json: drop the invalid object-form 'commands' field ({name,description} objects; the schema expects command path strings) so commands auto-discover from each plugin's commands/ directory.

Fix README install instructions: clarify Quick Install scope (commands + venv + creds, not skills); correct the Claude Code skill symlink target to the skill root (was desktop/, which would not load); fix the Claude Desktop import step.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

custom-skills/81-mac-optimizer/.claude-plugin/plugin.json

@@ -15,31 +15,5 @@
     "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-      "description": "Audit package managers (Homebrew, npm, pip, pyenv) for outdated packages and issues"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"
-    }
-  ]
+  "license": "MIT"
 }

custom-skills/91-multi-agent-guide/.claude-plugin/plugin.json

@@ -18,15 +18,5 @@
     "gemini",
     "codex"
   ],
-  "license": "MIT",
-  "commands": [
-    {
-      "name": "multi-agent-setup",
-      "description": "Quick setup for multi-agent collaboration"
-    },
-    {
-      "name": "setup-agents",
-      "description": "Full interactive multi-agent setup"
-    }
-  ]
+  "license": "MIT"
 }