feat: 月视图年月支持日期选择器跳转

- MonthHeader 新增 onYearMonthClick 回调，点击年月文字打开日期选择器
- CalendarMonthView 集成 DatePickerDialog，选择日期后调用 selectDate
- 复用现有 CalendarPager 动画，跨月跳转时自动平滑翻页

同时包含之前的改动：
- 临时隐藏 SplashActivity 入口，改由 MainActivity 作为 LAUNCHER
- benchmark build type 关闭 R8 混淆与资源压缩，保证 profile 可读性

app/build.gradle.kts

@@ -54,9 +54,11 @@ android {
             signingConfig = signingConfigs.getByName("debug")
             matchingFallbacks += listOf("release")
             // isDebuggable=false 使 macrobenchmark 在模拟器上稳定运行，且 Partial 编译模式可用。
-            // 代价是生成的 baseline-prof.txt / startup-prof.txt 会包含 R8 混淆后的类名；功能上仍然有效。
+            // 关闭混淆，保证生成的 baseline-prof.txt / startup-prof.txt 使用原始类名，
-            // 若需要可人工维护的可读 profile，请在真机上使用 debuggable build 或引入 Baseline Profile Gradle plugin。
+            // 避免 R8 混淆签名导致 profile 匹配与维护风险。
             isDebuggable = false
+            isMinifyEnabled = false
+            isShrinkResources = false
         }
     }
 

app/src/main/AndroidManifest.xml

@@ -9,20 +9,26 @@
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/Theme.YaYa">
+
+        <!--
+            SplashActivity 已临时禁用，不再作为应用入口。
+            如需恢复启动页，将下面的 MAIN/LAUNCHER intent-filter 从 MainActivity
+            移回 SplashActivity 即可。
+        -->
         <activity
             android:name=".SplashActivity"
             android:exported="true"
-            android:theme="@style/Theme.YaYa.Splash">
+            android:theme="@style/Theme.YaYa.Splash" />
+
+        <activity
+            android:name=".MainActivity"
+            android:exported="true">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
 
-        <activity
-            android:name=".MainActivity"
-            android:exported="true" />
-
         <activity
             android:name=".AboutActivity"
             android:exported="false" />

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

@@ -1,3 +1,5 @@
+@file:OptIn(ExperimentalMaterial3Api::class)
+
 package plus.rua.project.ui
 
 import androidx.compose.animation.AnimatedContent
@@ -42,11 +44,16 @@ import androidx.compose.material.icons.filled.Close
 import androidx.compose.material.icons.filled.Menu
 import androidx.compose.material3.Card
 import androidx.compose.material3.CardDefaults
+import androidx.compose.material3.DatePicker
+import androidx.compose.material3.DatePickerDialog
+import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.FloatingActionButton
 import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.material3.rememberDatePickerState
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.collectAsState
@@ -74,9 +81,12 @@ import kotlinx.coroutines.launch
 import kotlinx.datetime.LocalDate
 import kotlinx.datetime.Month
 import kotlinx.datetime.TimeZone
+import kotlinx.datetime.atStartOfDayIn
 import kotlinx.datetime.number
 import kotlinx.datetime.plus
+import kotlinx.datetime.toLocalDateTime
 import kotlinx.datetime.todayIn
+import kotlin.time.Instant
 import plus.rua.project.CalendarViewModel
 import plus.rua.project.ShiftKind
 import plus.rua.project.composeTraceBeginSection
@@ -125,6 +135,7 @@ fun CalendarMonthView(
     var rowHeightPx by remember { mutableIntStateOf(0) }
     var screenWidthPx by remember { mutableIntStateOf(0) }
     var isMenuExpanded by remember { mutableStateOf(false) }
+    var showDatePicker by remember { mutableStateOf(false) }
 
     // 视图切换时自动关闭菜单
     LaunchedEffect(isYearView) {
@@ -214,7 +225,8 @@ fun CalendarMonthView(
                                 month = currentMonth,
                                 weekNumber = weekNumber,
                                 showToday = selectedDate != today,
-                                onToday = onToday
+                                onToday = onToday,
+                                onYearMonthClick = { showDatePicker = true }
                             )
                             WeekdayHeader(
                                 modifier = Modifier.fillMaxWidth().padding(bottom = ROW_PADDING_DP.dp)
@@ -439,6 +451,34 @@ fun CalendarMonthView(
                 }
             }
         }
+
+        if (showDatePicker) {
+            val datePickerState = rememberDatePickerState(
+                initialSelectedDateMillis = selectedDate.toEpochMillis()
+            )
+            DatePickerDialog(
+                onDismissRequest = { showDatePicker = false },
+                confirmButton = {
+                    TextButton(
+                        onClick = {
+                            datePickerState.selectedDateMillis?.let { millis ->
+                                viewModel.selectDate(millis.toLocalDate())
+                            }
+                            showDatePicker = false
+                        }
+                    ) {
+                        Text("确定")
+                    }
+                },
+                dismissButton = {
+                    TextButton(onClick = { showDatePicker = false }) {
+                        Text("取消")
+                    }
+                }
+            ) {
+                DatePicker(state = datePickerState)
+            }
+        }
     }
 }
 
@@ -611,3 +651,19 @@ private fun MenuItem(
         )
     }
 }
+
+/**
+ * 将 [LocalDate] 转换为 UTC 午夜的 epoch 毫秒。
+ *
+ * 用于 DatePicker 初始选中值，与 [Long.toLocalDate] 成对使用。
+ */
+private fun LocalDate.toEpochMillis(): Long =
+    this.atStartOfDayIn(TimeZone.UTC).toEpochMilliseconds()
+
+/**
+ * 将 epoch 毫秒转换为 UTC 日期的 [LocalDate]。
+ *
+ * DatePicker 返回选中日期的 UTC 午夜毫秒，经此函数得到本地逻辑日期。
+ */
+private fun Long.toLocalDate(): LocalDate =
+    Instant.fromEpochMilliseconds(this).toLocalDateTime(TimeZone.UTC).date

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

@@ -34,6 +34,7 @@ import androidx.compose.ui.unit.sp
  * @param weekNumber 当前 ISO 周号
  * @param showToday 是否显示「今天」按钮（当 selectedDate ≠ today 时）
  * @param onToday 点击「今天」按钮跳转今天
+ * @param onYearMonthClick 点击"年月"文字打开日期选择器
  * @param modifier 外部布局修饰符
  */
 @Composable
@@ -43,6 +44,7 @@ fun MonthHeader(
     weekNumber: Int,
     showToday: Boolean,
     onToday: (() -> Unit)? = null,
+    onYearMonthClick: () -> Unit = {},
     modifier: Modifier = Modifier
 ) {
     Row(
@@ -66,7 +68,11 @@ fun MonthHeader(
             Text(
                 text = "${y}年${m}月",
                 color = MaterialTheme.colorScheme.onBackground,
-                style = MaterialTheme.typography.titleLarge
+                style = MaterialTheme.typography.titleLarge,
+                modifier = Modifier
+                    .clip(RoundedCornerShape(8.dp))
+                    .clickable(onClick = onYearMonthClick)
+                    .padding(horizontal = 4.dp, vertical = 2.dp)
             )
         }
         Spacer(modifier = Modifier.width(6.dp))