feat(viz-platform): create plugin structure (#177)

- Add plugins/viz-platform/ directory structure
- Create .claude-plugin/plugin.json with metadata
- Create .mcp.json pointing to viz-platform MCP server
- Create hooks/hooks.json with SessionStart hook
- Create symlink to mcp-servers/viz-platform
- Add plugin to marketplace.json

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.claude-plugin/marketplace.json

@@ -165,6 +165,22 @@
       "category": "data",
       "tags": ["pandas", "postgresql", "postgis", "dbt", "data-engineering", "etl"],
       "license": "MIT"
+    },
+    {
+      "name": "viz-platform",
+      "version": "1.0.0",
+      "description": "Visualization tools with Dash Mantine Components validation, Plotly charts, and theming",
+      "source": "./plugins/viz-platform",
+      "author": {
+        "name": "Leo Miranda",
+        "email": "leobmiranda@gmail.com"
+      },
+      "homepage": "https://gitea.hotserv.cloud/personal-projects/leo-claude-mktplace/src/branch/main/plugins/viz-platform/README.md",
+      "repository": "https://gitea.hotserv.cloud/personal-projects/leo-claude-mktplace.git",
+      "mcpServers": ["./.mcp.json"],
+      "category": "visualization",
+      "tags": ["dash", "plotly", "mantine", "charts", "dashboards", "theming", "dmc"],
+      "license": "MIT"
     }
   ]
 }