feat: add data-platform plugin (v4.0.0)

Add new data-platform plugin for data engineering workflows with:

MCP Server (32 tools):
- pandas operations (14 tools): read_csv, read_parquet, read_json,
  to_csv, to_parquet, describe, head, tail, filter, select, groupby,
  join, list_data, drop_data
- PostgreSQL/PostGIS (10 tools): pg_connect, pg_query, pg_execute,
  pg_tables, pg_columns, pg_schemas, st_tables, st_geometry_type,
  st_srid, st_extent
- dbt integration (8 tools): dbt_parse, dbt_run, dbt_test, dbt_build,
  dbt_compile, dbt_ls, dbt_docs_generate, dbt_lineage

Plugin Features:
- Arrow IPC data_ref system for DataFrame persistence across tool calls
- Pre-execution validation for dbt with `dbt parse`
- SessionStart hook for PostgreSQL connectivity check (non-blocking)
- Hybrid configuration (system ~/.config/claude/postgres.env + project .env)
- Memory management with 100k row limit and chunking support

Commands: /initial-setup, /ingest, /profile, /schema, /explain, /lineage, /run
Agents: data-ingestion, data-analysis

Test suite: 71 tests covering config, data store, pandas, postgres, dbt tools

Addresses data workflow issues from personal-portfolio project:
- Lost data after multiple interactions (solved by Arrow IPC data_ref)
- dbt 1.9+ syntax deprecation (solved by pre-execution validation)
- Ungraceful PostgreSQL error handling (solved by SessionStart hook)

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

.claude-plugin/marketplace.json

@@ -149,6 +149,22 @@
       "category": "development",
       "tags": ["code-review", "pull-requests", "security", "quality"],
       "license": "MIT"
+    },
+    {
+      "name": "data-platform",
+      "version": "1.0.0",
+      "description": "Data engineering tools with pandas, PostgreSQL/PostGIS, and dbt integration",
+      "source": "./plugins/data-platform",
+      "author": {
+        "name": "Leo Miranda",
+        "email": "leobmiranda@gmail.com"
+      },
+      "homepage": "https://gitea.hotserv.cloud/personal-projects/leo-claude-mktplace/src/branch/main/plugins/data-platform/README.md",
+      "repository": "https://gitea.hotserv.cloud/personal-projects/leo-claude-mktplace.git",
+      "mcpServers": ["./.mcp.json"],
+      "category": "data",
+      "tags": ["pandas", "postgresql", "postgis", "dbt", "data-engineering", "etl"],
+      "license": "MIT"
     }
   ]
 }