refactor(prompts): add comprehensive partial_close guidance to adaptive.txt

Add detailed guidance chapter for dynamic TP/SL management and partial close operations.

## Changes

- New chapter: "动态止盈止损与部分平仓指引" (Dynamic TP/SL & Partial Close Guidance)
- Inserted between "可用动作" (Actions) and "决策流程" (Decision Flow) sections
- 4 key guidance points covering:
  1. Partial close best practices (use clear percentages like 25%/50%/75%)
  2. Reassessing remaining position after partial exit
  3. Proper use cases for update_stop_loss / update_take_profit
  4. Multi-stage exit strategy requirements

## Benefits

- ✅ Provides concrete operational guidelines for AI decision-making
- ✅ Clarifies when and how to use partial_close effectively
- ✅ Emphasizes remaining position management (prevents "orphan" positions)
- ✅ Aligns with existing backend support for partial_close action

## Background

While adaptive.txt already lists partial_close as an available action,
it lacked detailed operational guidance. This enhancement fills that gap
by providing specific percentages, use cases, and multi-stage exit examples.

Backend (decision/engine.go) already validates partial_close with
close_percentage field, so this is purely a prompt enhancement with
no code changes required.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

prompts/adaptive.txt

@@ -97,6 +97,15 @@
 
 ---
 
+# 动态止盈止损与部分平仓指引
+
+- `partial_close` 用于锁定阶段性收益或降低风险，建议使用清晰比例（如 25% / 50% / 75%），并说明目的（例："锁定关键阻力前利润""减半仓等待回踩确认"）。
+- 执行部分平仓后，应评估是否需要同步上调止损 / 下调止盈，确保剩余仓位符合新的风险回报结构。
+- `update_stop_loss` / `update_take_profit` 优先用于顺势推进（如跟踪新高新低），避免在无新证据下放宽止损。
+- 若计划分批退出，请在 `reasoning` 中描述剩余仓位的策略与失效条件，避免出现"减仓后不知道如何处理剩余部位"的情况。
+
+---
+
 # 决策流程（严格顺序）
 
 ## 第 0 步：疑惑检查