```

feat(AI): 集成MNN推理引擎替换MLX作为主AI运行时

- 引入MNN(alibaba) + Arm SME2 + CPU作为主AI运行时，支持A19/iPhone17的
  SME2和A17的NEON加速
- 添加MLX Swift作为兜底GPU推理方案，实现双后端切换机制
- 使用单一Qwen3.5-2B多模态模型(1.2GB)，替代原有的LLM+VL分离架构
- 实现InferenceEngine.current引擎选择逻辑，真机默认MNN，模拟器回退MLX
- 更新AIAgent架构，通过MNNLLMBridge(ObjC++) → MNNBackend进行推理
- 修改队列机制防止并发推理导致OOM，使用信号量闸门控制显存占用
- 更新文档中的技术栈说明、模块边界和周次交付计划
```

康康/Features/Diary/MedicationLogSheet.swift

@@ -0,0 +1,133 @@
+import SwiftUI
+import SwiftData
+
+/// 「写日记 · 用药」:记一次服用流水 —— 选药(药品库或手输)+ 剂量 + 时间
+/// → 带 `DiaryEntry.medicationTag` 的日记,进「记录」时间线的「用药」分类。
+///
+/// 与药品库(`Medication`,master 清单)分层:这里是「某次吃了多少、什么时候吃的」。
+/// 嵌套 sheet,自带保存 / 取消(同 `SymptomStartSheet`),关闭后回到写日记页。
+struct MedicationLogSheet: View {
+    @Environment(\.modelContext) private var ctx
+    @Environment(\.dismiss) private var dismiss
+
+    @Query(sort: \Medication.updatedAt, order: .reverse)
+    private var library: [Medication]
+
+    /// 选中的药品库药;手输模式为 nil。
+    @State private var selectedMed: Medication?
+    /// 手输药名(药品库为空,或想记不在库里的药)。与 selectedMed 互斥。
+    @State private var manualName = ""
+    @State private var dosage = ""
+    @State private var takenAt: Date = .now
+
+    private var resolvedName: String {
+        (selectedMed?.name ?? manualName).trimmingCharacters(in: .whitespacesAndNewlines)
+    }
+    private var canSave: Bool { !resolvedName.isEmpty }
+
+    var body: some View {
+        NavigationStack {
+            Form {
+                Section {
+                    if library.isEmpty {
+                        TextField(String(appLoc: "药名,如:缬沙坦胶囊"), text: $manualName)
+                            .foregroundStyle(Tj.Palette.text)
+                    } else {
+                        ForEach(library) { m in
+                            Button { select(m) } label: { medRow(m) }
+                                .buttonStyle(.plain)
+                        }
+                        HStack(spacing: 8) {
+                            Image(systemName: "pencil")
+                                .foregroundStyle(Tj.Palette.text3)
+                            TextField(String(appLoc: "或手动输入药名"), text: $manualName)
+                                .foregroundStyle(Tj.Palette.text)
+                                .onChange(of: manualName) { _, v in
+                                    if !v.trimmingCharacters(in: .whitespaces).isEmpty {
+                                        selectedMed = nil
+                                    }
+                                }
+                        }
+                    }
+                } header: {
+                    Text("吃了哪个药")
+                } footer: {
+                    if library.isEmpty {
+                        Text("药品库还没有药,可在「记录 · 药品库」拍药盒或手动添加。这里直接手输也行。")
+                    }
+                }
+
+                Section {
+                    TextField(String(appLoc: "剂量,如:1 片 / 80mg"), text: $dosage)
+                        .foregroundStyle(Tj.Palette.text)
+                } header: {
+                    Text("剂量")
+                }
+
+                Section {
+                    DatePicker(String(appLoc: "时间"), selection: $takenAt, in: ...Date.now)
+                } header: {
+                    Text("时间")
+                }
+            }
+            .scrollContentBackground(.hidden)
+            .background(Tj.Palette.sand.ignoresSafeArea())
+            .navigationTitle("记录用药")
+            .navigationBarTitleDisplayMode(.inline)
+            .toolbar {
+                ToolbarItem(placement: .topBarLeading) {
+                    Button(String(appLoc: "取消")) { dismiss() }
+                }
+                ToolbarItem(placement: .topBarTrailing) {
+                    Button(String(appLoc: "保存")) { save() }
+                        .fontWeight(.semibold)
+                        .disabled(!canSave)
+                }
+            }
+        }
+    }
+
+    private func medRow(_ m: Medication) -> some View {
+        let on = selectedMed === m
+        return HStack(spacing: 10) {
+            Image(systemName: on ? "checkmark.circle.fill" : "circle")
+                .foregroundStyle(on ? Tj.Palette.ink : Tj.Palette.text3)
+            VStack(alignment: .leading, spacing: 2) {
+                Text(m.name)
+                    .foregroundStyle(Tj.Palette.text)
+                if !m.detailLine.isEmpty {
+                    Text(m.detailLine)
+                        .font(.tjScaled( 11))
+                        .foregroundStyle(Tj.Palette.text3)
+                }
+            }
+            Spacer(minLength: 0)
+        }
+        .contentShape(Rectangle())
+    }
+
+    private func select(_ m: Medication) {
+        selectedMed = m
+        manualName = ""
+    }
+
+    private func save() {
+        guard canSave else { return }
+        // content 单行:「药名 [规格] · 剂量」。剂量进正文,时间用 createdAt 承载。
+        // 与 TimelineEntry.firstLine / TimelineEntryDetailView.medicationLines 单行解析兼容。
+        var line = resolvedName
+        if let s = selectedMed?.strength, !s.isEmpty { line += " \(s)" }
+        let dose = dosage.trimmingCharacters(in: .whitespacesAndNewlines)
+        if !dose.isEmpty { line += " · \(dose)" }
+
+        let entry = DiaryEntry(content: line, createdAt: takenAt, tags: [DiaryEntry.medicationTag])
+        ctx.insert(entry)
+        try? ctx.save()
+        dismiss()
+    }
+}
+
+#Preview {
+    MedicationLogSheet()
+        .modelContainer(for: [Medication.self, DiaryEntry.self, Asset.self], inMemory: true)
+}