fix: remove stale deals.csv references, add extract+store to launch_backtest

- FilePaths struct: remove deals_csv/deals_json fields (deals go to DB only)
- save_metadata: stop writing stale CSV/JSON paths to pipeline_metadata.json
- get_backtest_status: remove deals.csv artifact check (was unused in logic)
- get_backtest_crash_info: check DB deal count and metrics.json instead of deals.csv
- export_report: remove unused _deals_path variable
- launch_backtest: monitor_backtest_completion now calls extract_and_store when
  report found — extracts metrics+deals, registers report in DB, deletes htm file

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

src/tools/definitions/utility.rs

@@ -289,7 +289,7 @@ pub fn tool_get_wine_prefix_info() -> Value {
 pub fn tool_get_backtest_crash_info() -> Value {
     json!({
         "name": "get_backtest_crash_info",
-        "description": "Investigate backtest crashes/failures. Checks for incomplete markers, missing deals.csv, error logs. Can scan recent reports.",
+        "description": "Investigate backtest crashes/failures. Checks for incomplete markers, missing metrics.json, DB deal count, error logs. Can scan recent reports.",
         "inputSchema": {
             "type": "object",
             "properties": {