docs(architecture): 完成技术验证 S1–S4，确定 FR-M2-05/06 目标值

- spikes/：Word 转 PDF（Gotenberg）、格式识别、原句坐标、DeepSeek 抽取四项验证代码与两版提示词；样本派生产物和 .env 不进 git
- tech-validation.md：完整结论。四项都可行：WPS 字体字符集要修正并改用行高调整过的字体；格式识别不需要 Docling；表格内切句待改进；抽取需第三道依据校验与规则兜底
- architecture.md：§3.5 加预处理与字体包，§3.6 证据校验改为三道，§10 回填结论
- 03 功能需求与 decisions.md（TV1）：召回 ≥ 99%、采纳准确率 ≥ 95%、页码 100%、高亮正文 ≥ 98% / 表格 ≥ 95%

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

spikes/s1-convert/toc_truth.py

@@ -0,0 +1,50 @@
+"""S1 替代真值：DOCX 目录里缓存的页码（生成文档的软件排版时写入）。
+比较「各标题之间相隔的页数」，消除页码起始值的影响。"""
+import json, re, sys, zipfile, pathlib
+import pdfplumber
+
+OUT = pathlib.Path(__file__).parent / "out"
+norm = lambda s: re.sub(r"[\s　·.…\-—_]", "", s)
+
+def toc_entries(docx):
+    x = zipfile.ZipFile(docx).read("word/document.xml").decode()
+    ents = []
+    for p in re.findall(r"<w:p[ >].*?</w:p>", x, re.S):
+        if "PAGEREF" not in p:
+            continue
+        # 段落里 PAGEREF 字段之前的文字是标题，字段结果是缓存页码
+        before, after = p.split("PAGEREF", 1)
+        title = norm("".join(re.findall(r"<w:t[^>]*>([^<]*)</w:t>", before)))
+        num = re.findall(r"<w:t[^>]*>(\d+)</w:t>", after)
+        if title and num:
+            ents.append((title, int(num[0])))
+    return ents
+
+def heading_pages(pdf_path, titles):
+    with pdfplumber.open(pdf_path) as pdf:
+        texts = [norm(pg.extract_text() or "") for pg in pdf.pages]
+    found = {}
+    for t in titles:
+        key = t[:18]
+        hits = [i for i, tx in enumerate(texts) if key in tx]
+        # 跳过目录页本身：取最后一个出现位置之前、且不在前 6 页的第一个命中
+        body = [i for i in hits if i >= 4]
+        found[t] = body[0] + 1 if body else None
+    return found
+
+rows = {}
+for sid in ["S03", "S04", "S06"]:
+    ents = toc_entries(OUT / "fixed-docx" / f"{sid}.docx")
+    rows[sid] = {"entries": len(ents)}
+    for cfg in ["A-fixed", "B-fixed", "C10-fixed", "C13-fixed"]:
+        hp = heading_pages(OUT / cfg / f"{sid}.pdf", [t for t, _ in ents])
+        pairs = [(n, hp[t]) for t, n in ents if hp[t]]
+        if len(pairs) < 2:
+            rows[sid][cfg] = None; continue
+        (c0, p0), (c1, p1) = pairs[0], pairs[-1]
+        span_t, span_p = c1 - c0, p1 - p0
+        dev = [abs((p - p0) - (c - c0)) for c, p in pairs]
+        rows[sid][cfg] = {"matched": len(pairs), "span_truth": span_t, "span_pdf": span_p,
+                          "span_err_pct": round(100 * (span_p - span_t) / span_t, 1), "max_dev_pages": max(dev)}
+    print(sid, json.dumps(rows[sid], ensure_ascii=False))
+(OUT / "toc_truth.json").write_text(json.dumps(rows, ensure_ascii=False, indent=1))