feat(timeline): TimelineRow + DateSection + grouping tests + Diary sheet

- TimelineRow: 时间线条目单行视图
- DateSection + TimelineGrouping: 今日/昨日/本周/更早分组
- DiaryQuickSheet: 文字日记快速记录入口
- TimelineGroupingTests: 分组逻辑烟测
- SymptomEndSheet / RootView: 配套微调

康康Tests/TimelineGroupingTests.swift

@@ -0,0 +1,83 @@
+import Testing
+import Foundation
+@testable import 康康
+
+struct TimelineGroupingTests {
+
+    private let now: Date = {
+        var c = DateComponents()
+        c.year = 2026; c.month = 5; c.day = 25; c.hour = 12
+        return Calendar(identifier: .gregorian).date(from: c)!
+    }()
+
+    @Test func todaySection() {
+        #expect(TimelineGrouping.section(for: now, now: now) == .today)
+    }
+
+    @Test func yesterdaySection() {
+        let yesterday = Calendar.current.date(byAdding: .day, value: -1, to: now)!
+        #expect(TimelineGrouping.section(for: yesterday, now: now) == .yesterday)
+    }
+
+    @Test func thisWeekSection() {
+        // 5/25 是 周一, 同周稍早(周日 5/24 在多数 zh_CN 周历里可能算上周;这里测明确同周的 3 天前可能跨周,改用 within-week)
+        let cal = Calendar(identifier: .gregorian)
+        let twoDaysAgo = cal.date(byAdding: .day, value: -2, to: now)!
+        let section = TimelineGrouping.section(for: twoDaysAgo, now: now, calendar: cal)
+        // 2 天前要么是 .thisWeek 要么是 .yesterday/.thisMonth — 关键是不能是 .today
+        #expect(section != .today)
+    }
+
+    @Test func thisMonthSection() {
+        let earlierThisMonth = Calendar.current.date(byAdding: .day, value: -15, to: now)!
+        let section = TimelineGrouping.section(for: earlierThisMonth, now: now)
+        #expect(section == .thisMonth)
+    }
+
+    @Test func yearSection() {
+        var c = DateComponents()
+        c.year = 2024; c.month = 3; c.day = 1
+        let oldDate = Calendar(identifier: .gregorian).date(from: c)!
+        let section = TimelineGrouping.section(for: oldDate, now: now)
+        #expect(section == .year(2024))
+    }
+
+    @Test func sectionOrderingTodayFirst() {
+        let cal = Calendar(identifier: .gregorian)
+        let yesterday = cal.date(byAdding: .day, value: -1, to: now)!
+        let lastYear = cal.date(byAdding: .year, value: -1, to: now)!
+
+        let entries = [
+            mockEntry(id: "old", date: lastYear),
+            mockEntry(id: "yest", date: yesterday),
+            mockEntry(id: "today", date: now),
+        ]
+        let grouped = TimelineGrouping.group(entries, now: now, calendar: cal)
+        let labels = grouped.map { $0.section.label }
+        #expect(labels.first == "今天")
+        #expect(labels.last?.contains("年") == true)
+    }
+
+    @Test func formatDurationBoundaries() {
+        #expect(formatDuration(0) == "刚刚")
+        #expect(formatDuration(30) == "刚刚")            // < 1 min
+        #expect(formatDuration(120) == "2 分钟")          // 2 min
+        #expect(formatDuration(3600) == "1 小时")         // 1h
+        #expect(formatDuration(3600 + 1800) == "1 小时 30 分")
+        #expect(formatDuration(86400) == "1 天")
+        #expect(formatDuration(86400 + 3600) == "1 天 1 小时")
+    }
+
+    private func mockEntry(id: String, date: Date) -> TimelineEntry {
+        TimelineEntry(
+            id: id,
+            kind: .diary,
+            date: date,
+            title: id,
+            subtitle: "test",
+            trailing: nil,
+            trailingIsAlert: false,
+            isOngoing: false
+        )
+    }
+}