fix(ci): add test environment variables to prevent import errors

Issue: CI failing with "UndefinedValueError: SECRET_KEY not found"
Root Cause: Settings modules load env vars at import time, before
conftest.py can set TESTING=true

Fix: Add minimal test environment variables to CI workflow
- SECRET_KEY for security module
- Database credentials (not used, but required for imports)
- API keys (fake values for testing, not used)
- Reddit credentials (not used in tests)

All values are fake/test-only and do not expose real credentials.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.github/workflows/test.yml

@@ -35,6 +35,26 @@ jobs:
           uv run pytest --cov=src --cov-report=xml --cov-report=term
         env:
           PYTHONPATH: src
+          # Test environment variables
+          TESTING: "true"
+          DEBUG: "false"
+          SECRET_KEY: "test-secret-key-for-ci-only"
+          # Database (not used in tests, but required for imports)
+          SQL_DIALECT: "sqlite"
+          LOCAL_DB_UN: "test"
+          LOCAL_DB_PW: "test"
+          LOCAL_DB_DB: "test"
+          LOCAL_DB_HOST: "localhost"
+          LOCAL_DB_PORT: "5432"
+          # API keys (not used in tests, but required for imports)
+          OPENAI_API_KEY: "sk-test-fake-key"
+          ANTHROPIC_API_KEY: "sk-ant-test-fake-key"
+          TAVILY_API_KEY: "test-key"
+          # Reddit (not used in tests)
+          REDDIT_CLIENT_ID: "test"
+          REDDIT_CLIENT_SECRET: "test"
+          REDDIT_USER_AGENT: "test"
+          REDDIT_SUBREDDIT: "test"
 
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@v4