fix(ground): one 위치 control on the card and clearer layer labels

- The 위치 buttons duplicated the 형상 옵션 chips above the card. The chips
  stay the one place for 위치 (only the default is selectable until Q6).
- The water-level row lays out as a flex row, so its label and input do not
  overlap.
- The 연암 상면 caption sits just under the line instead of over the band label.

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

src/view/ground-svg.ts

@@ -38,7 +38,8 @@ export function groundSectionSvg(input: PierInput, model: PierModel): string {
     parts.push(`<text x="8" y="${(top + bottom) / 2 + 4}" font-size="12" fill="#18212B">${escapeText(row.name)}</text>`);
     if (row.name === SUPPORT_STRATUM) {
       parts.push(`<line x1="0" y1="${top}" x2="${WIDTH}" y2="${top}" stroke="#5B4A2E" stroke-width="2"></line>`);
-      parts.push(`<text x="8" y="${top - 4}" font-size="12" fill="#18212B">연암층 상면 EL ${upper.toFixed(3)}</text>`);
+      // Caption just under the line, so it does not collide with the label of the band above.
+      parts.push(`<text x="8" y="${top + 14}" font-size="12" fill="#18212B">연암층 상면 EL ${upper.toFixed(3)}</text>`);
     }
     upper = row.bottomEl;
   });