perf: 提取农历/节气计算为 LunarCache LRU 缓存，添加启动预计算

- 新增 LunarCache 单例，LinkedHashMap(accessOrder=true) 实现 LRU 语义，
  @Synchronized 保护并发，容量 800 条，超限时淘汰 20%
- CalendarViewModel init 中在 Default 线程预计算当前月前后各 1 个月
- DayCell 移除内联 computeDayCellInfo 和 mutableMap 缓存，统一使用 LunarCache

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

core/src/main/kotlin/plus/rua/project/CalendarViewModel.kt

@@ -9,6 +9,7 @@ import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.setValue
 import androidx.compose.runtime.withFrameNanos
 import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.launch
 import kotlinx.datetime.DatePeriod
@@ -19,6 +20,7 @@ import kotlinx.datetime.minus
 import kotlinx.datetime.number
 import kotlinx.datetime.plus
 import kotlinx.datetime.todayIn
+import plus.rua.project.LunarCache
 import plus.rua.project.ui.COLLAPSE_THRESHOLD
 import plus.rua.project.ui.FLING_VELOCITY_THRESHOLD_DP
 import kotlin.time.Clock
@@ -72,6 +74,42 @@ class CalendarViewModel(
 ) {
     private val today: LocalDate = clock.todayIn(TimeZone.currentSystemDefault())
 
+    init {
+        coroutineScope.launch(Dispatchers.Default) {
+            // 预计算当前月前后各 1 个月
+            val currentYear = today.year
+            val currentMonth = today.month.number
+
+            @Suppress("DEPRECATION") // monthNumber 无替代 API
+            val monthsToPrecompute = listOf(
+                currentMonth - 1 to currentYear,
+                currentMonth to currentYear,
+                currentMonth + 1 to currentYear
+            ).map { (month, year) ->
+                when {
+                    month < 1 -> 12 to year - 1
+                    month > 12 -> 1 to year + 1
+                    else -> month to year
+                }
+            }
+
+            monthsToPrecompute.forEach { (month, year) ->
+                val firstOfMonth = LocalDate(year, month, 1)
+                val offset = firstOfMonth.dayOfWeek.ordinal
+                val startDate = firstOfMonth.minus(DatePeriod(days = offset))
+                val nextMonth = if (month == 12) LocalDate(year + 1, 1, 1) else LocalDate(year, month + 1, 1)
+                val daysInMonth = nextMonth.minus(DatePeriod(days = 1)).day
+                val rows = ((offset + daysInMonth - 1) / 7) + 1
+                val totalDays = rows * 7
+
+                val dates = (0 until totalDays).map { i ->
+                    startDate.plus(DatePeriod(days = i))
+                }
+                LunarCache.precompute(dates)
+            }
+        }
+    }
+
     var selectedDate by mutableStateOf(today)
         private set
 

core/src/main/kotlin/plus/rua/project/LunarCache.kt

@@ -0,0 +1,106 @@
+package plus.rua.project
+
+import com.tyme.solar.SolarDay
+import kotlinx.datetime.LocalDate
+
+/**
+ * 农历/节气/节假日信息缓存。
+ *
+ * 使用 LinkedHashMap（accessOrder=true）实现 LRU 语义，读写速度优于 ConcurrentHashMap。
+ * 通过 @Synchronized 保护并发访问；冷启动时主线程单线程访问，偏向锁使其几乎零开销。
+ */
+object LunarCache {
+    private const val MAX_SIZE = 800
+
+    @Suppress("DEPRECATION")
+    private val cache = LinkedHashMap<LocalDate, DayCellInfo>(256, 0.75f, true)
+
+    /**
+     * 获取指定日期的信息，缓存 miss 时同步计算。
+     */
+    @Synchronized
+    @Suppress("DEPRECATION") // monthNumber 无替代 API
+    fun getOrCompute(date: LocalDate): DayCellInfo {
+        cache[date]?.let { return it }
+        val computed = compute(date)
+        cache[date] = computed
+        trimIfNeeded()
+        return computed
+    }
+
+    /**
+     * 批量预计算并填充缓存。
+     *
+     * @param dates 日期列表
+     */
+    @Synchronized
+    fun precompute(dates: List<LocalDate>) {
+        dates.forEach { date ->
+            if (!cache.containsKey(date)) {
+                cache[date] = compute(date)
+            }
+        }
+        trimIfNeeded()
+    }
+
+    private fun trimIfNeeded() {
+        if (cache.size > MAX_SIZE) {
+            val toRemove = (cache.size * 0.2).toInt().coerceAtLeast(1)
+            val iterator = cache.keys.iterator()
+            var removed = 0
+            while (iterator.hasNext() && removed < toRemove) {
+                iterator.next()
+                iterator.remove()
+                removed++
+            }
+        }
+    }
+
+    @Suppress("DEPRECATION") // monthNumber 无替代 API
+    private fun compute(date: LocalDate): DayCellInfo {
+        val solarDay = SolarDay.fromYmd(date.year, date.monthNumber, date.day)
+        val holidayBadge = solarDay.getLegalHoliday()?.let { if (it.isWork()) "班" else "休" }
+        val lunarDay = solarDay.getLunarDay()
+
+        // 农历传统节日（仅当天）
+        val lunarFestival = lunarDay.getFestival()
+        if (lunarFestival != null) {
+            return DayCellInfo(lunarFestival.getName(), true, holidayBadge)
+        }
+
+        // 节气（当天才显示）
+        val termDay = solarDay.getTermDay()
+        if (termDay.getDayIndex() == 0) {
+            return DayCellInfo(termDay.getSolarTerm().getName(), true, holidayBadge)
+        }
+
+        // 公历节日（仅当天）
+        val solarFestival = solarDay.getFestival()
+        if (solarFestival != null) {
+            return DayCellInfo(solarFestival.getName(), true, holidayBadge)
+        }
+
+        // 默认：农历日期
+        val name = lunarDay.getName()
+        val text = if (name == "初一") {
+            val lunarMonth = lunarDay.getLunarMonth()
+            "${lunarMonth.getName()}月"
+        } else {
+            name
+        }
+        return DayCellInfo(text, false, holidayBadge)
+    }
+}
+
+/**
+ * 日期单元格显示信息。
+ *
+ * @param annotationText 底部标注文字（农历/节气/节日）
+ * @param isAnnotationHighlight 是否为高亮标注（节日/节气）
+ * @param holidayBadge 法定调休角标（"班"/"休"/null）
+ */
+data class DayCellInfo(
+    val annotationText: String,
+    val isAnnotationHighlight: Boolean,
+    val holidayBadge: String?
+)

core/src/main/kotlin/plus/rua/project/ui/DayCell.kt

@@ -34,48 +34,10 @@ import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 import androidx.compose.ui.zIndex
-import com.tyme.solar.SolarDay
 import kotlinx.datetime.LocalDate
+import plus.rua.project.LunarCache
 import plus.rua.project.ShiftKind
 
-// P0-C: 静态缓存 SolarDay 计算结果，避免 Pager 滑动/切换时重复创建对象触发 GC
-@Suppress("DEPRECATION") // monthNumber 无替代 API
-private fun computeDayCellInfo(date: LocalDate): Triple<String, Boolean, String?> {
-    val solarDay = SolarDay.fromYmd(date.year, date.monthNumber, date.day)
-    val holidayBadge = solarDay.getLegalHoliday()?.let { if (it.isWork()) "班" else "休" }
-    val lunarDay = solarDay.getLunarDay()
-
-    // 农历传统节日（仅当天）
-    val lunarFestival = lunarDay.getFestival()
-    if (lunarFestival != null) {
-        return Triple(lunarFestival.getName(), true, holidayBadge)
-    }
-
-    // 节气（当天才显示）
-    val termDay = solarDay.getTermDay()
-    if (termDay.getDayIndex() == 0) {
-        return Triple(termDay.getSolarTerm().getName(), true, holidayBadge)
-    }
-
-    // 公历节日（仅当天）
-    val solarFestival = solarDay.getFestival()
-    if (solarFestival != null) {
-        return Triple(solarFestival.getName(), true, holidayBadge)
-    }
-
-    // 默认：农历日期
-    val name = lunarDay.getName()
-    val text = if (name == "初一") {
-        val lunarMonth = lunarDay.getLunarMonth()
-        "${lunarMonth.getName()}月"
-    } else {
-        name
-    }
-    return Triple(text, false, holidayBadge)
-}
-
-private val dayCellInfoCache = mutableMapOf<LocalDate, Triple<String, Boolean, String?>>()
-
 enum class DayCellState {
     NORMAL, OTHER_MONTH, TODAY, SELECTED, SELECTED_TODAY
 }
@@ -105,6 +67,9 @@ fun DayCell(
     onClick: () -> Unit,
     modifier: Modifier = Modifier
 ) {
+    val (annotationText, isAnnotationHighlight, holidayBadge) = remember(date) {
+        LunarCache.getOrCompute(date)
+    }
     val currentState = when {
         isSelected && isToday -> DayCellState.SELECTED_TODAY
         isSelected -> DayCellState.SELECTED
@@ -162,11 +127,6 @@ fun DayCell(
 
     val selectedOutlineColor = MaterialTheme.colorScheme.primary
 
-    // P0-C: 使用静态缓存避免每次重组时重复创建 SolarDay 对象
-    val (annotationText, isAnnotationHighlight, holidayBadge) = remember(date) {
-        dayCellInfoCache.getOrPut(date) { computeDayCellInfo(date) }
-    }
-
     val lunarColor by transition.animateColor(
         transitionSpec = { tween(150, easing = FastOutSlowInEasing) },
         label = "lunarColor"