Initial commit: Python SDK for Dragonchain (Prime)

Synchronous Python SDK modeled on prime-sdk-go. Provides DC1-HMAC-SHA256
auth, dataclass models, and resource clients for system, transaction,
transaction-type, smart-contract, and block endpoints, plus a YAML
credentials loader.

.gitignore

@@ -0,0 +1,50 @@
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# Distribution / packaging
+build/
+dist/
+*.egg-info/
+*.egg
+.eggs/
+
+# Virtual environments
+.venv/
+venv/
+env/
+ENV/
+
+# Test / coverage
+.pytest_cache/
+.coverage
+coverage.xml
+htmlcov/
+.tox/
+
+# Type checkers / linters
+.mypy_cache/
+.ruff_cache/
+
+# IDEs
+.idea/
+.vscode/
+*.swp
+*.swo
+*~
+.DS_Store
+
+# Credentials and local config
+credentials.yaml
+credentials.yml
+.env
+.env.local
+*.key
+*.pem
+*.p12
+
+# OS specific
+Thumbs.db
+ehthumbs.db
+._*