feat: replace 2 m placeholder with station pattern table from the workbook (Task 5)

Source: RAG 지보패턴현황_20260918.xlsx, sheet 참고_지보패턴현황, 당진방향 table
(4+740..5+500, 42 contiguous rows). Lining pattern (M column) per station now
drives the lining colour and the viewer readout. Daesan table kept as reference
only (WL-4 there, not applied). Drawing patterns E-1, E-2, RP-2, WL-3 are in
neither table and stay [미확정].

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A5Cun3RHQKna9qxE6ybZ4A

scripts/extract_pattern_table.py

@@ -0,0 +1,48 @@
+#!/usr/bin/env python3
+"""Extract the 당진방향 station pattern table from 참고_지보패턴현황 (read-only).
+Rows 55..96 of the sheet: C=start STA, G=end STA, J=length, M=lining pattern
+(지보패턴), O=실시설계 excavation class (blank = continues the row above),
+Q=굴착공법, T=비고. Also extracts the 대산방향 table (rows 13..49) for reference.
+Usage: extract_pattern_table.py <xlsx> <out_dir>"""
+import csv, os, sys
+import openpyxl
+
+SRC, OUT = sys.argv[1], sys.argv[2]
+wb = openpyxl.load_workbook(SRC, read_only=True, data_only=True)
+ws = wb["참고_지보패턴현황"]
+rows = {r: row for r, row in enumerate(ws.iter_rows(min_row=1, max_row=114, max_col=33, values_only=True), start=1)}
+
+
+def table(r0, r1, tag):
+    out, last_o = [], None
+    for r in range(r0, r1 + 1):
+        row = rows[r]
+        try:
+            a, b = float(row[2]), float(row[6])
+        except (TypeError, ValueError):
+            continue
+        m = (row[12] or "").strip() if isinstance(row[12], str) else row[12]
+        o_raw = row[14]
+        o = o_raw if o_raw not in (None, "") else last_o
+        last_o = o
+        remark = (row[19] or "") if isinstance(row[19], str) else ""
+        out.append({"direction": tag, "source_row": r, "sta_from": a, "sta_to": b,
+                    "length_m": row[9], "lining_pattern": m or ("개착부" if "개착" in remark else ""),
+                    "excavation": o or "", "excavation_inherited": o_raw in (None, ""),
+                    "method": (row[16] or "") if isinstance(row[16], str) else "",
+                    "remark": remark})
+    return out
+
+
+south = table(55, 96, "당진")
+north = table(13, 49, "대산")
+os.makedirs(OUT, exist_ok=True)
+cols = list(south[0].keys())
+for name, data in [("pattern_stations_dangjin.csv", south), ("pattern_stations_daesan_ref.csv", north)]:
+    with open(os.path.join(OUT, name), "w", encoding="utf-8", newline="") as fh:
+        w = csv.DictWriter(fh, fieldnames=cols)
+        w.writeheader()
+        w.writerows(data)
+print("dangjin rows", len(south), "range", south[0]["sta_from"], "->", south[-1]["sta_to"])
+print("daesan rows", len(north), "range", north[0]["sta_from"], "->", north[-1]["sta_to"])
+print("blank lining pattern rows (dangjin):", [(d["source_row"], d["remark"]) for d in south if not d["lining_pattern"]])