chore: standardize configuration, logging, and error handling across blockchain node and coordinator API

- Add infrastructure.md and workflow files to .gitignore to prevent sensitive info leaks
- Change blockchain node mempool backend default from memory to database for persistence
- Refactor blockchain node logger with StructuredLogFormatter and AuditLogger (consistent with coordinator)
- Add structured logging fields: service, module, function, line number
- Unify coordinator config with Database

docs/8_development/2_setup.md

@@ -0,0 +1,76 @@
+---
+title: Development Setup
+description: Set up your development environment for AITBC
+---
+
+# Development Setup
+
+This guide helps you set up a development environment for building on AITBC.
+
+## Prerequisites
+
+- Python 3.8+
+- Git
+- Docker (optional)
+- Node.js 16+ (for frontend development)
+
+## Local Development
+
+### 1. Clone Repository
+```bash
+git clone https://github.com/aitbc/aitbc.git
+cd aitbc
+```
+
+### 2. Install Dependencies
+```bash
+# Python dependencies
+pip install -r requirements.txt
+
+# Development dependencies
+pip install -r requirements-dev.txt
+```
+
+### 3. Start Services
+```bash
+# Using Docker Compose
+docker-compose -f docker-compose.dev.yml up -d
+
+# Or start individually
+aitbc dev start
+```
+
+### 4. Verify Setup
+```bash
+# Check services
+aitbc status
+
+# Run tests
+pytest
+```
+
+## IDE Setup
+
+### VS Code
+Install extensions:
+- Python
+- Docker
+- GitLens
+
+### PyCharm
+Configure Python interpreter and enable Docker integration.
+
+## Environment Variables
+
+Create `.env` file:
+```bash
+AITBC_API_KEY=your_dev_key
+AITBC_BASE_URL=http://localhost:8011
+AITBC_NETWORK=testnet
+```
+
+## Next Steps
+
+- [API Authentication](api-authentication.md)
+- [Python SDK](sdks/python.md)
+- [Examples](examples.md)