**feat(docs): add comprehensive architecture documentation for Brainy**

- **Documentation Additions**:
  - Created `brainy_architecture_diagram.md` to detail Brainy's architecture using diagrams and structured descriptions:
    - Added overviews of the system, core architecture, and augmentation pipeline.
    - Defined data models, graph structures, storage architecture, and performance optimizations.
    - Explained vector search engine design, HNSW index structure, and usage flow examples.
  - Developed `brainy_architecture_visual.md` to complement the architecture with visual aids in Mermaid.js:
    - Provided detailed flowcharts, mind maps, and sequence diagrams for system components and data flow.

- **Purpose**:
  - Provide in-depth technical insights into Brainy's architecture for developers and stakeholders.
  - Enhance understanding of the system's core design principles with easy-to-follow diagrams and examples.

dev/README.md

@@ -0,0 +1,53 @@
+# Development Tools & Documentation
+
+This directory contains development tools, scripts, and documentation files that are not included in the published npm package.
+
+## Directory Structure
+
+```
+dev/
+├── docs/           # Development documentation files
+│   ├── brainy_architecture_diagram.md
+│   ├── PDF_GENERATION_GUIDE.md
+│   ├── QUICK_PDF_SETUP.md
+│   └── brainy_architecture_visual.md
+├── scripts/        # Development scripts
+│   └── generate-architecture-pdf.js
+└── README.md       # This file
+```
+
+## Scripts
+
+### generate-architecture-pdf.js
+
+Generates a professional PDF documentation of Brainy's architecture using:
+- Material Design styling
+- Custom SVG diagrams
+- Comprehensive content from README.md
+- Professional visual presentation
+
+**Usage:**
+```bash
+# From project root
+node dev/scripts/generate-architecture-pdf.js
+
+# Or add to package.json scripts
+npm run generate-docs
+```
+
+**Requirements:**
+- puppeteer (for PDF generation)
+
+**Output:**
+- `docs/Brainy_Architecture_Documentation.pdf`
+
+## Documentation Files
+
+- **brainy_architecture_diagram.md**: ASCII art diagrams of system architecture
+- **PDF_GENERATION_GUIDE.md**: Detailed guide for PDF generation setup
+- **QUICK_PDF_SETUP.md**: Quick setup instructions
+- **brainy_architecture_visual.md**: Visual architecture documentation
+
+## NPM Package Exclusion
+
+This entire `dev/` directory is excluded from the published npm package via `.npmignore` to keep the package size minimal and focused on the core library functionality.