feat: initial oracle-26ai-vector MCP server

MCP server exposing Oracle 23ai as a RAG vector store backed by
OCI GenAI Cohere Embed v4 (1536 dims). Three tools:
- insert_document: embed + store a text chunk
- update_document: re-embed + update an existing chunk
- search_similar: cosine similarity search (VECTOR_DISTANCE)

Uses python-oracledb thin mode with wallet (config_dir only).
Configured for Claude Code via ~/.claude/settings.json.

.gitignore

@@ -0,0 +1,21 @@
+# Environment
+.env
+*.env
+
+# Python
+__pycache__/
+*.py[cod]
+*.pyo
+.venv/
+venv/
+*.egg-info/
+dist/
+build/
+
+# IDE
+.vscode/
+.idea/
+*.swp
+
+# OS
+.DS_Store