feat(ai-services): add Python FastAPI AI/ML services container

Create libs/ai-services/ with FastAPI app providing:
- POST /avm/predict — XGBoost-backed property price prediction (heuristic fallback)
- POST /avm/extract-features — Vietnamese NLP feature extraction from listing text
- POST /moderation/check — content moderation with rule-based flagging
- GET /health — health check endpoint

Includes Dockerfile (Python 3.12), docker-compose integration, Pydantic models,
and 9 passing tests covering all endpoints.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

libs/ai-services/pyproject.toml

@@ -0,0 +1,30 @@
+[project]
+name = "goodgo-ai-services"
+version = "0.1.0"
+description = "AI/ML services for Goodgo Platform — AVM, feature extraction, moderation"
+requires-python = ">=3.12"
+dependencies = [
+    "fastapi>=0.115.0",
+    "uvicorn[standard]>=0.32.0",
+    "xgboost>=2.1.0",
+    "numpy>=1.26.0",
+    "underthesea>=6.8.0",
+    "pydantic>=2.9.0",
+    "pydantic-settings>=2.5.0",
+    "httpx>=0.27.0",
+]
+
+[project.optional-dependencies]
+dev = [
+    "pytest>=8.3.0",
+    "pytest-asyncio>=0.24.0",
+    "httpx>=0.27.0",
+]
+
+[build-system]
+requires = ["setuptools>=75.0"]
+build-backend = "setuptools.backends._legacy:_Backend"
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+asyncio_mode = "auto"