fix(spreadsheet): 단위 Φ 앞붙이기 — 강제 글 낫표 뒤에 붙임 · 식은 그대로(81-5)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MgChuAcyBqUkhHMTXomQC7

A00_Common/spreadsheet/spreadsheet_toolbar.ts

@@ -103,6 +103,15 @@ export function attachUnitToFormat(code: string, unit: string): string {
   return `"${unit}"` + plain;
 }
 
+/** 앞 단위를 글 앞에 붙임(「300」 → 「Φ300」) — 글 낫표(강제 글 `'300`)는 맨 앞에 두고 그 뒤에
+ * 붙임(`'Φ300` → 칸 값 「Φ300」) · 이미 붙어 있거나 식(`=`)이면 그대로 */
+export function prefixUnit(text: string, unit: string): string {
+  if (text.startsWith("=")) return text;
+  const lead = text.startsWith("'") ? "'" : "";
+  const body = text.slice(lead.length);
+  return body.startsWith(unit) ? text : lead + unit + body;
+}
+
 /** 활성 칸에 지금 걸린 서식 — 칸 자기 것 없으면 열 · 행 · 시트 기본(`Sheet.기본.서식`) · 그다음 0. */
 function styleAt(ctx: SpreadsheetContext, r: number, c: number): CellStyle {
   const sheet = ctx.sheet();
@@ -405,13 +414,18 @@ export function mountToolbar(ctx: SpreadsheetContext): PartHandle {
     if (ctx.editor.editing()) {
       const active = document.activeElement;
       if (active instanceof HTMLTextAreaElement && ctx.root.contains(active)) {
-        const front = UNIT_PREFIX.includes(unit);
-        const s = front ? 0 : (active.selectionStart ?? active.value.length);
-        const e = front ? 0 : (active.selectionEnd ?? active.value.length);
         const was = active.selectionStart ?? active.value.length;
-        active.value = active.value.slice(0, s) + unit + active.value.slice(e);
-        const at = front ? was + unit.length : s + unit.length;
-        active.setSelectionRange(at, at);
+        if (UNIT_PREFIX.includes(unit)) {
+          const next = prefixUnit(active.value, unit);
+          const at = was + next.length - active.value.length;
+          active.value = next;
+          active.setSelectionRange(at, at);
+        } else {
+          const s = was;
+          const e = active.selectionEnd ?? active.value.length;
+          active.value = active.value.slice(0, s) + unit + active.value.slice(e);
+          active.setSelectionRange(s + unit.length, s + unit.length);
+        }
         active.dispatchEvent(new Event("input", { bubbles: true }));
       }
     } else if (unitAsFormat.checked) {
@@ -422,11 +436,7 @@ export function mountToolbar(ctx: SpreadsheetContext): PartHandle {
       const sheet = ctx.sheet();
       const key = toA1(r, c);
       const now = cellToText(sheet.칸[key]);
-      const text = UNIT_PREFIX.includes(unit)
-        ? now.startsWith(unit)
-          ? now
-          : unit + now // 앞 단위 — 「300」 → 「Φ300」
-        : now + unit;
+      const text = UNIT_PREFIX.includes(unit) ? prefixUnit(now, unit) : now + unit;
       ctx.dispatch({ 종류: "칸", 시트: sheet.id, 칸: { [key]: textToCell(text, sheet.칸[key]) } });
     }
     renderRecent(pushRecentUnit(unit));