Add: Unit tests for habit_bot and stock_tracker

- tests/test_habit_bot.py: Habit tracking, food logging, keto guidance
- tests/test_stock_tracker.py: Portfolio management, P&L calculation
- pytest.ini: Pytest configuration
- Updated Jenkinsfile: Emphasized testing stages before build

Pipeline stages:
1. Code Quality Gates (lint + security)
2. Unit Tests (pytest with coverage)
3. Integration Tests (Oracle, Telegram, Gitea)
4. Build (only after tests pass)
5. Deploy to Staging

tests/__init__.py

@@ -0,0 +1 @@
+# Tests package