feat(prediction): 원 분석 기능 — 중심점/반경 입력으로 원형 오염 면적 계산

- 원 분석 버튼 클릭 시 입력 폼 토글 (중심 위도, 경도, 반경 km)
- 사고 지점 좌표를 기본값으로 자동 설정
- πr² 면적, 2πr 둘레 계산 결과 표시
- 결과: 오염 면적(km²), 원 둘레(km), 반경(km), 중심 좌표

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/tabs/prediction/components/RightPanel.tsx

@@ -18,6 +18,11 @@ export function RightPanel({ onOpenBacktrack, onOpenRecalc, onOpenReport, detail
   const [shipExpanded, setShipExpanded] = useState(false)
   const [insuranceExpanded, setInsuranceExpanded] = useState(false)
   const [polygonResult, setPolygonResult] = useState<{ areaKm2: number; perimeterKm: number; particleCount: number; hullPoints: number } | null>(null)
+  const [showCircleInput, setShowCircleInput] = useState(false)
+  const [circleCenterLat, setCircleCenterLat] = useState('')
+  const [circleCenterLon, setCircleCenterLon] = useState('')
+  const [circleRadiusKm, setCircleRadiusKm] = useState('')
+  const [circleResult, setCircleResult] = useState<{ areaKm2: number; circumferenceKm: number; centerLat: number; centerLon: number; radiusKm: number } | null>(null)
 
   return (
     <div className="w-[300px] min-w-[300px] bg-bg-1 border-l border-border flex flex-col">
@@ -60,12 +65,115 @@ export function RightPanel({ onOpenBacktrack, onOpenRecalc, onOpenReport, detail
               📐 다각형 분석
             </button>
             <button
-              onClick={() => alert('원 분석 기능은 향후 오픈 예정입니다.')}
+              onClick={() => {
+                setShowCircleInput(!showCircleInput)
+                // 사고 지점 좌표를 기본값으로 설정
+                if (!showCircleInput && detail?.spill) {
+                  if (!circleCenterLat) setCircleCenterLat(String(detail.spill.lat ?? ''))
+                  if (!circleCenterLon) setCircleCenterLon(String(detail.spill.lon ?? ''))
+                }
+              }}
               className="flex-1 py-2.5 px-2 rounded text-[10px] font-bold font-korean border cursor-pointer transition-colors hover:brightness-110"
-              style={{ background: 'rgba(6,182,212,0.1)', border: '1px solid rgba(6,182,212,0.3)', color: 'var(--cyan)' }}>
+              style={showCircleInput
+                ? { background: 'rgba(6,182,212,0.2)', border: '1px solid var(--cyan)', color: 'var(--cyan)' }
+                : { background: 'rgba(6,182,212,0.1)', border: '1px solid rgba(6,182,212,0.3)', color: 'var(--cyan)' }
+              }>
               ⭕ 원 분석
             </button>
           </div>
+
+          {/* 원 분석 입력 폼 */}
+          {showCircleInput && (
+            <div className="flex flex-col gap-2 p-2.5 bg-bg-0 border border-[rgba(6,182,212,0.2)] rounded-md mb-2">
+              <div className="text-[9px] font-bold text-primary-cyan font-korean">⭕ 원 분석 — 중심점 · 반경 입력</div>
+              <div className="grid grid-cols-2 gap-1.5">
+                <div>
+                  <label className="text-[8px] text-text-3 font-korean block mb-0.5">중심 위도 (°N)</label>
+                  <input
+                    type="number"
+                    step="0.0001"
+                    value={circleCenterLat}
+                    onChange={e => setCircleCenterLat(e.target.value)}
+                    placeholder="예: 34.7312"
+                    className="w-full px-2 py-1.5 bg-bg-3 border border-border rounded text-[10px] font-mono text-text-1 outline-none focus:border-[var(--cyan)] transition-colors"
+                  />
+                </div>
+                <div>
+                  <label className="text-[8px] text-text-3 font-korean block mb-0.5">중심 경도 (°E)</label>
+                  <input
+                    type="number"
+                    step="0.0001"
+                    value={circleCenterLon}
+                    onChange={e => setCircleCenterLon(e.target.value)}
+                    placeholder="예: 127.6845"
+                    className="w-full px-2 py-1.5 bg-bg-3 border border-border rounded text-[10px] font-mono text-text-1 outline-none focus:border-[var(--cyan)] transition-colors"
+                  />
+                </div>
+              </div>
+              <div>
+                <label className="text-[8px] text-text-3 font-korean block mb-0.5">반경 (km)</label>
+                <input
+                  type="number"
+                  step="0.1"
+                  min="0.1"
+                  value={circleRadiusKm}
+                  onChange={e => setCircleRadiusKm(e.target.value)}
+                  placeholder="예: 3.0"
+                  className="w-full px-2 py-1.5 bg-bg-3 border border-border rounded text-[10px] font-mono text-text-1 outline-none focus:border-[var(--cyan)] transition-colors"
+                />
+              </div>
+              <button
+                onClick={() => {
+                  const lat = parseFloat(circleCenterLat)
+                  const lon = parseFloat(circleCenterLon)
+                  const r = parseFloat(circleRadiusKm)
+                  if (isNaN(lat) || isNaN(lon) || isNaN(r) || r <= 0) {
+                    alert('중심 좌표와 반경을 올바르게 입력하세요.')
+                    return
+                  }
+                  const areaKm2 = Math.PI * r * r
+                  const circumferenceKm = 2 * Math.PI * r
+                  setCircleResult({ areaKm2, circumferenceKm, centerLat: lat, centerLon: lon, radiusKm: r })
+                }}
+                disabled={!circleCenterLat || !circleCenterLon || !circleRadiusKm}
+                className="w-full py-2 rounded text-[10px] font-bold font-korean cursor-pointer transition-colors"
+                style={{
+                  background: (circleCenterLat && circleCenterLon && circleRadiusKm) ? 'rgba(6,182,212,0.15)' : 'var(--bg3)',
+                  border: (circleCenterLat && circleCenterLon && circleRadiusKm) ? '1px solid var(--cyan)' : '1px solid var(--bd)',
+                  color: (circleCenterLat && circleCenterLon && circleRadiusKm) ? 'var(--cyan)' : 'var(--t3)',
+                }}
+              >
+                ⭕ 원 면적 계산
+              </button>
+            </div>
+          )}
+
+          {/* 원 분석 결과 */}
+          {circleResult && (
+            <div className="flex flex-col gap-1.5 mb-2">
+              <div className="text-[9px] font-bold text-primary-cyan font-korean mb-0.5">⭕ 원 분석 결과</div>
+              <div className="grid grid-cols-2 gap-1">
+                <div className="text-center py-2 px-1 bg-bg-0 border border-border rounded">
+                  <div className="text-sm font-extrabold font-mono text-primary-cyan">{circleResult.areaKm2.toFixed(2)}</div>
+                  <div className="text-[7px] text-text-3 font-korean">오염 면적 (km²)</div>
+                </div>
+                <div className="text-center py-2 px-1 bg-bg-0 border border-border rounded">
+                  <div className="text-sm font-extrabold font-mono text-status-orange">{circleResult.circumferenceKm.toFixed(1)}</div>
+                  <div className="text-[7px] text-text-3 font-korean">원 둘레 (km)</div>
+                </div>
+                <div className="text-center py-2 px-1 bg-bg-0 border border-border rounded">
+                  <div className="text-sm font-extrabold font-mono text-text-1">{circleResult.radiusKm.toFixed(1)}</div>
+                  <div className="text-[7px] text-text-3 font-korean">반경 (km)</div>
+                </div>
+                <div className="text-center py-2 px-1 bg-bg-0 border border-border rounded">
+                  <div className="text-[9px] font-bold font-mono text-text-2">{circleResult.centerLat.toFixed(4)}°N</div>
+                  <div className="text-[9px] font-bold font-mono text-text-2">{circleResult.centerLon.toFixed(4)}°E</div>
+                  <div className="text-[7px] text-text-3 font-korean">중심 좌표</div>
+                </div>
+              </div>
+            </div>
+          )}
+
           {polygonResult && (
             <div className="flex flex-col gap-1.5">
               <div className="text-[9px] font-bold text-purple-400 font-korean mb-0.5">📐 Convex Hull 다각형 분석 결과</div>