feat(adc): UN 标定完成、标定脚本归集到 test/host/cal/

- UN 通道 5 点最小二乘标定完成：r=555.382141, b=-1, 残差 0.038%, R²=0.99999967
- UA/IA/UN 三路 VALID 置位，保护解卡
- ROM 默认值更新为当前标定值（ADC_CAL_R_Q16_VOLT=555.144958）
- UB/UC/UN 通过 104 写入 ROM 默认值，config.ini 同步
- cal_fit.py 新增 ROLD 表自动读取，不再需要手传 --r-old
- 执行卡精简至 126 行，新增 cal_collect.py 采集脚本与 ROLD 填表
- 标定脚本（cal_fit/cal_write/cal_collect）归集到 test/host/cal/
- 全库文档路径引用同步更新（8 文件）
- UN 当前态文档改写：明确零序电压 U0 语义、本台架未接线状态
- 删除已失效的外部知识底座文档链接

test/host/cal/cal_write.py

@@ -0,0 +1,92 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""两点标定写入器：C_SE_NC_1 两段写下发 r/b，C_RD 读回复核。
+
+复用台架已验收主站库 test/host/iec104_master.py（不重写协议层）。
+地址（App/algo/run_par.c run_par_104_write）：r = 0x8050+slot，
+b = 0x8048+slot；slot UA0/UN3/IA4。执行卡：
+docs/测试说明/专项验证/ADC多点标定执行流程.md §4。
+
+用法：
+  python test/host/cal_write.py --r 0x8050=995.99 --b 0x8048=-1 \
+      --read 0x8050,0x8048 --expect 995.99,-1
+  python test/host/cal_write.py --read 0x8050,0x8054 --expect 995.99,29.52
+
+写入顺序刻意**先 r 后 b**：b 走 adc_cal_set() 置 VALID 位，而 VALID 要求
+r 已在带——先让 r 就位，语义干净。--b 必须是整数码值。
+PN（否定确认）= 执行段拒绝：看串口 `[ERR] set ch=... rejected` 行。
+输出纯 ASCII，可直接重定向归档为台架证据；exit 0 全过 / 1 有失败 / 2 连接或协议错误。
+"""
+import argparse
+import os
+import sys
+
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+import bench_defaults                                   # noqa: E402
+import iec104_master as m104                            # noqa: E402
+
+
+def parse_pair(text):
+    addr_s, val_s = text.split("=", 1)
+    return int(addr_s, 0), float(val_s)
+
+
+def main():
+    ap = argparse.ArgumentParser()
+    ap.add_argument("--ip", default=bench_defaults.DEVICE_IP)
+    ap.add_argument("--port", type=int, default=2404)
+    ap.add_argument("--r", action="append", default=[],
+                    help="0xADDR=FLOAT ratio write (repeatable, issued first)")
+    ap.add_argument("--b", action="append", default=[],
+                    help="0xADDR=INT zero-code write (repeatable, sets VALID)")
+    ap.add_argument("--read", default="",
+                    help="comma-separated IOA list, C_RD readback")
+    ap.add_argument("--expect", default="",
+                    help="comma-separated expected values, same order as --read")
+    a = ap.parse_args()
+
+    reads = [x.strip() for x in a.read.split(",") if x.strip()]
+    expects = [float(x) for x in a.expect.split(",")] if a.expect else []
+    if not a.r and not a.b and not reads:
+        ap.error("need at least one --r / --b / --read")
+
+    ck = m104.Checks()
+    try:
+        m = m104.Master(a.ip, a.port)
+    except Exception as exc:
+        print("CONNECT FAIL: %r" % (exc,))
+        return 2
+
+    try:
+        m._send(m104.u_frame(m104.U_STARTDT_ACT), "U  STARTDT act")
+        ck.add("startdt_con", m.wait_event(
+            lambda e: e[0] == "startdt_con", 5.0) is not None)
+
+        for text in a.r:                                   # 1) ratio first
+            addr, val = parse_pair(text)
+            m104.se_write(m, ck, addr, val, "r_%04X" % addr)
+
+        for text in a.b:                                   # 2) zero + VALID
+            addr, val = parse_pair(text)
+            if abs(val - round(val)) > 1e-6:
+                print("WARN b=%s not an integer code, truncated to %.0f"
+                      % (text, round(val)))
+                val = float(round(val))
+            m104.se_write(m, ck, addr, val, "b_%04X" % addr)
+
+        for i, addr_s in enumerate(reads):
+            want = expects[i] if i < len(expects) else 0.0
+            m104.rd_set(m, ck, int(addr_s, 0), want, "rd_%s" % addr_s)
+    finally:
+        m.close()
+
+    bad = [n for n, ok, _ in ck.items if not ok]
+    print("SUMMARY %s total=%d fail=%d" %
+          ("PASS" if not bad else "FAIL", len(ck.items), len(bad)))
+    if bad:
+        print("FAILED: %s" % ", ".join(bad))
+    return 0 if not bad else 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())