P3 Stream J: widget data repository (DataStore-backed)

Ports iOS WidgetDataManager.swift semantics. DTO + JSON serialization +
pending-completion tracking + stats (overdueCount / dueWithin7 / dueWithin8To30).
Same-process DataStore is sufficient for Glance widgets.

Unblocks Streams K (widgets) / L (scheduler) / M (actions).

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

composeApp/src/androidMain/kotlin/com/tt/honeyDue/widget/WidgetTaskDto.kt

@@ -0,0 +1,49 @@
+package com.tt.honeyDue.widget
+
+import kotlinx.serialization.Serializable
+
+/**
+ * DTO persisted to the widget DataStore as JSON, mirroring iOS
+ * `WidgetDataManager.swift`'s on-disk task representation.
+ *
+ * iOS field map (for reference — keep in sync):
+ *  - id              Int    (task id)
+ *  - title           String
+ *  - priority        Int    (priority id)
+ *  - dueDate         String?   ISO-8601 ("yyyy-MM-dd" or full datetime)
+ *  - isOverdue       Bool
+ *  - daysUntilDue    Int
+ *  - residenceId     Int
+ *  - residenceName   String
+ *  - categoryIcon    String    SF-symbol-style identifier
+ *  - completed       Bool
+ *
+ * Kotlin uses [Long] for ids to accommodate any server-side auto-increment range.
+ */
+@Serializable
+data class WidgetTaskDto(
+    val id: Long,
+    val title: String,
+    val priority: Long,
+    val dueDate: String?,
+    val isOverdue: Boolean,
+    val daysUntilDue: Int,
+    val residenceId: Long,
+    val residenceName: String,
+    val categoryIcon: String,
+    val completed: Boolean
+)
+
+/**
+ * Summary metrics computed from the cached task list.
+ *
+ * Windows match iOS `calculateMetrics` semantics:
+ *  - overdueCount     tasks with isOverdue == true
+ *  - dueWithin7       tasks with 0 <= daysUntilDue <= 7
+ *  - dueWithin8To30   tasks with 8 <= daysUntilDue <= 30
+ */
+data class WidgetStats(
+    val overdueCount: Int,
+    val dueWithin7: Int,
+    val dueWithin8To30: Int
+)