fix: correct Claude Code plugin install commands and add marketplace.json

.claude-plugin/marketplace.json

@@ -0,0 +1,18 @@
+{
+  "name": "socraticode",
+  "owner": {
+    "name": "Giancarlo Erra",
+    "email": "giancarlo@altaire.com"
+  },
+  "metadata": {
+    "description": "SocratiCode — codebase intelligence plugin for Claude Code"
+  },
+  "plugins": [
+    {
+      "name": "socraticode",
+      "source": "./",
+      "description": "Codebase intelligence — semantic search workflows, dependency graph analysis, and context artifact exploration",
+      "category": "development"
+    }
+  ]
+}

README.md

@@ -90,8 +90,9 @@ The first Qdrant‑based MCP/Claude Plugin/Skill that pairs auto‑managed, zero
 
 **Claude Code** — install the plugin (recommended, includes workflow skills for best results):
 
-```bash
-claude plugin add --from-github giancarloerra/socraticode
+```
+/plugin marketplace add giancarloerra/socraticode
+/plugin install socraticode@socraticode
 ```
 
 Or as MCP only (without skills):
@@ -296,8 +297,9 @@ before reading any files directly.
 
 The SocratiCode plugin bundles both the MCP server and workflow skills that teach Claude how to use the tools effectively. One install gives you everything:
 
-```bash
-claude plugin add --from-github giancarloerra/socraticode
+```
+/plugin marketplace add giancarloerra/socraticode
+/plugin install socraticode@socraticode
 ```
 
 The plugin includes: