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/Features/Timeline/DateSection.swift

@@ -0,0 +1,74 @@
+import Foundation
+
+enum DateSection: Hashable {
+    case today
+    case yesterday
+    case thisWeek
+    case thisMonth
+    case year(Int)
+
+    var label: String {
+        switch self {
+        case .today:        return "今天"
+        case .yesterday:    return "昨天"
+        case .thisWeek:     return "本周"
+        case .thisMonth:    return "本月"
+        case .year(let y):  return "\(y) 年"
+        }
+    }
+
+    var sortIndex: Int {
+        switch self {
+        case .today:       return 0
+        case .yesterday:   return 1
+        case .thisWeek:    return 2
+        case .thisMonth:   return 3
+        case .year(let y): return 10_000 - y
+        }
+    }
+}
+
+enum TimelineGrouping {
+    static func section(for date: Date,
+                        now: Date = .now,
+                        calendar: Calendar = .current) -> DateSection {
+        if calendar.isDateInToday(date) { return .today }
+        if calendar.isDateInYesterday(date) { return .yesterday }
+        if calendar.isDate(date, equalTo: now, toGranularity: .weekOfYear) {
+            return .thisWeek
+        }
+        if calendar.isDate(date, equalTo: now, toGranularity: .month) {
+            return .thisMonth
+        }
+        let year = calendar.component(.year, from: date)
+        return .year(year)
+    }
+
+    static func group(_ entries: [TimelineEntry],
+                      now: Date = .now,
+                      calendar: Calendar = .current)
+    -> [(section: DateSection, items: [TimelineEntry])] {
+        var buckets: [DateSection: [TimelineEntry]] = [:]
+        for entry in entries {
+            let key = section(for: entry.date, now: now, calendar: calendar)
+            buckets[key, default: []].append(entry)
+        }
+        return buckets
+            .map { ($0.key, $0.value.sorted { $0.date > $1.date }) }
+            .sorted { $0.0.sortIndex < $1.0.sortIndex }
+    }
+}
+
+func formatDuration(_ interval: TimeInterval) -> String {
+    let totalMinutes = Int(max(0, interval) / 60)
+    let days = totalMinutes / (60 * 24)
+    let hours = (totalMinutes % (60 * 24)) / 60
+    let minutes = totalMinutes % 60
+
+    if days > 0 && hours > 0 { return "\(days) 天 \(hours) 小时" }
+    if days > 0 { return "\(days) 天" }
+    if hours > 0 && minutes > 0 { return "\(hours) 小时 \(minutes) 分" }
+    if hours > 0 { return "\(hours) 小时" }
+    if minutes > 0 { return "\(minutes) 分钟" }
+    return "刚刚"
+}

康康/Features/Timeline/TimelineRow.swift

@@ -0,0 +1,73 @@
+import SwiftUI
+
+struct TimelineRow: View {
+    let entry: TimelineEntry
+
+    var body: some View {
+        HStack(spacing: 12) {
+            ZStack {
+                RoundedRectangle(cornerRadius: 8, style: .continuous)
+                    .fill(entry.kind.accent.opacity(0.12))
+                Image(systemName: entry.kind.icon)
+                    .font(.system(size: 14, weight: .semibold))
+                    .foregroundStyle(entry.kind.accent)
+            }
+            .frame(width: 36, height: 36)
+            .overlay(alignment: .topTrailing) {
+                if entry.isOngoing {
+                    Circle()
+                        .fill(Tj.Palette.brick)
+                        .frame(width: 7, height: 7)
+                        .overlay(Circle().strokeBorder(Tj.Palette.sand, lineWidth: 1.5))
+                        .offset(x: 3, y: -3)
+                }
+            }
+
+            VStack(alignment: .leading, spacing: 2) {
+                Text("\(entry.date.timelineLabel) · \(entry.subtitle)")
+                    .font(.system(size: 11))
+                    .tracking(0.3)
+                    .foregroundStyle(Tj.Palette.text3)
+                    .lineLimit(1)
+                Text(entry.title)
+                    .font(.system(size: 14, weight: .medium))
+                    .foregroundStyle(Tj.Palette.text)
+                    .lineLimit(1)
+                    .truncationMode(.tail)
+            }
+            Spacer(minLength: 8)
+            if let trailing = entry.trailing {
+                Text(trailing)
+                    .font(.system(size: 12, weight: .semibold, design: .monospaced))
+                    .foregroundStyle(entry.trailingIsAlert ? Tj.Palette.brick : Tj.Palette.text2)
+                    .lineLimit(1)
+                    .fixedSize()
+            }
+        }
+        .padding(12)
+        .tjCard(bordered: true)
+    }
+}
+
+extension Date {
+    var timelineLabel: String {
+        let cal = Calendar.current
+        if cal.isDateInToday(self) {
+            return self.formatted(date: .omitted, time: .shortened)
+        }
+        if cal.isDateInYesterday(self) {
+            return "昨天 " + self.formatted(date: .omitted, time: .shortened)
+        }
+        let now = Date.now
+        if cal.isDate(self, equalTo: now, toGranularity: .year) {
+            let f = DateFormatter()
+            f.locale = Locale(identifier: "zh_CN")
+            f.dateFormat = "M 月 d 日"
+            return f.string(from: self)
+        }
+        let f = DateFormatter()
+        f.locale = Locale(identifier: "zh_CN")
+        f.dateFormat = "yyyy 年 M 月 d 日"
+        return f.string(from: self)
+    }
+}