Clean up unused files, organize structure, update docs

- Delete obsolete files: data_fetcher_old.py, market_old.py, base_strategy.py (root),
  strategy_sma_cross.py, and old architecture remnants (address_monitor.py,
  position_monitor.py, trade_log.py, wallet_data.py, whale_tracker.py)
- Delete zero-byte Docker artifacts and runtime files (clp_hedger.log,
  clp_hedger/hedge_status.json)
- Move one-off utility scripts to scripts/ directory
- Move example/template files to .temp/ directory
- Update .gitignore: add entries for clp_hedger.log, clp_hedger/hedge_status.json,
  Docker layer hash files, Using, Running, and backups/
- Update .dockerignore: add clp_hedger.log, clp_hedger/hedge_status.json, backups/
- Create example config files: _data/strategies.json.example,
  _data/backtesting_conf.json.example, _data/coin_precision.json.example
- Update GEMINI.md: remove outdated session summaries and duplicate review section
- Update review.md: add cleanup status section, update remaining recommendations
- Update MIGRATION_PLAN.md: mark completed phases, update file references
- Update DOCKER_MIGRATION_GUIDE.md: update import_csv.py path reference

.gitignore

@@ -22,6 +22,9 @@ _data/*.json
 # Ignore all log files
 _logs/
 
+# Ignore backups
+backups/
+
 # --- SDK ---
 # Ignore all contents of the sdk directory
 sdk/
@@ -30,6 +33,15 @@ sdk/
 # Ignore custom agents directory
 agents/
 
+# Ignore CLP hedger runtime log and status
+clp_hedger.log
+clp_hedger/hedge_status.json
+
+# Ignore Docker layer hash files and artifacts
+/[0-9a-f]{12}
+/Running
+/Using
+
 # Ignore temporary files and examples
 .temp/