refactor: reorganize project structure into tests/, data/, logs/

- Move all backtest/simulation scripts to tests/
  - Add sys.path.insert to each script for correct import resolution
- Move pkl cache files to data/ (git-ignored)
- Move log files to logs/ (git-ignored)
- Update main.py: trading.log path → logs/trading.log
- Add ecosystem.config.js: pm2 log paths → logs/pm2*.log
- Update .gitignore: ignore data/ and logs/ instead of *.pkl/*.log
- core/fng.py: increase cache TTL 3600→86400s (API updates daily at KST 09:00)

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

ecosystem.config.js

@@ -0,0 +1,15 @@
+module.exports = {
+  apps: [
+    {
+      name: "upbit-trader",
+      script: "main.py",
+      interpreter: ".venv/bin/python3",
+      cwd: "/Users/joungmin/workspaces/upbit-trader",
+      out_file: "logs/pm2.log",
+      error_file: "logs/pm2-error.log",
+      log_date_format: "YYYY-MM-DD HH:mm:ss",
+      autorestart: true,
+      watch: false,
+    },
+  ],
+};