Implement Gemini batch sentiment scoring; replace FinBERT/transformers

- Migrate news_engine to google-genai SDK with gemini-2.5-flash-lite
- Batch all headlines into one API call per scan (30 calls -> 1)
- In-memory cache keyed by headline hash; fallback to keyword scoring
- Update requirements.txt: add google-genai, python-dotenv; remove transformers
- Add .gitignore; update CLAUDE.md with Gemini live section

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,17 @@
+# Secrets
+.env
+.env.local
+
+# Editor / tooling
+.claude/
+.vscode/
+.idea/
+
+# Python (note: __pycache__/ is intentionally tracked in this repo — see CLAUDE.md)
+*.egg-info/
+.venv/
+venv/
+
+# OS
+.DS_Store
+Thumbs.db