refactor: split large files and clean up project structure

- Rename experience/ to telemetry/ for clarity
- Split 15+ large Go files (800-2200 lines) into focused modules:
  kernel/engine.go, backtest/runner.go, market/data.go, store/position.go,
  api/handler_trader.go, trader/auto_trader_grid.go, and 9 exchange traders
- Split frontend monoliths: types.ts, api.ts, AITradersPage.tsx, BacktestPage.tsx
  into domain-specific modules with barrel re-exports
- Remove stale files: screenshots, .yml.old, pyproject.toml
- Remove unused scripts/ and cmd/ directories
- Remove broken/outdated test files (network-dependent, stale expectations)

web/src/components/backtest/BacktestDecisionsTab.tsx

@@ -0,0 +1,36 @@
+import { motion } from 'framer-motion'
+import { DecisionCard } from '../trader/DecisionCard'
+import type { Language } from '../../i18n/translations'
+import type { DecisionRecord } from '../../types'
+
+interface BacktestDecisionsTabProps {
+  decisions: DecisionRecord[] | undefined
+  language: Language
+  tr: (key: string) => string
+}
+
+export function BacktestDecisionsTab({ decisions, language, tr }: BacktestDecisionsTabProps) {
+  return (
+    <motion.div
+      key="decisions"
+      initial={{ opacity: 0 }}
+      animate={{ opacity: 1 }}
+      exit={{ opacity: 0 }}
+      className="space-y-3 max-h-[500px] overflow-y-auto"
+    >
+      {decisions && decisions.length > 0 ? (
+        decisions.map((d) => (
+          <DecisionCard
+            key={`${d.cycle_number}-${d.timestamp}`}
+            decision={d}
+            language={language}
+          />
+        ))
+      ) : (
+        <div className="py-12 text-center" style={{ color: '#5E6673' }}>
+          {tr('decisionTrail.emptyHint')}
+        </div>
+      )}
+    </motion.div>
+  )
+}