feat(observability): add structured application logging

Emit correlated JSON logs from the API and FunASR services, propagate request IDs to the client, and configure bounded opt-in Docker logging.

Document the host-wide Grafana/Loki query workflow and keep observability deployment ownership outside the application repository.

pages/defaults/index.ts

@@ -1,4 +1,10 @@
-import { getApiErrorMessage, getProfileDefaults, updateProfileDefaults } from '../../utils/api'
+import {
+  copyApiRequestId,
+  getApiErrorMessage,
+  getApiRequestId,
+  getProfileDefaults,
+  updateProfileDefaults
+} from '../../utils/api'
 import type { StudentProfileDefaults } from '../../utils/types'
 
 const grades = ['初一', '初二', '初三']
@@ -30,7 +36,8 @@ Page({
     maximumDuration,
     loading: false,
     saving: false,
-    errorMessage: ''
+    errorMessage: '',
+    errorRequestId: ''
   },
 
   onShow() {
@@ -38,7 +45,7 @@ Page({
   },
 
   async loadDefaults(showSuccess = false) {
-    this.setData({ loading: true, errorMessage: '' })
+    this.setData({ loading: true, errorMessage: '', errorRequestId: '' })
     try {
       const defaults = await getProfileDefaults()
       this.setData({
@@ -49,7 +56,7 @@ Page({
       })
       if (showSuccess) wx.showToast({ title: '预设已刷新', icon: 'success' })
     } catch (error) {
-      this.setData({ errorMessage: getApiErrorMessage(error) })
+      this.setData({ errorMessage: getApiErrorMessage(error), errorRequestId: getApiRequestId(error) })
     } finally {
       this.setData({ loading: false })
     }
@@ -59,6 +66,10 @@ Page({
     void this.loadDefaults(true)
   },
 
+  copyRequestId() {
+    copyApiRequestId(this.data.errorRequestId)
+  },
+
   onGradeChange(event: PickerEvent) {
     this.setData({ 'defaults.grade': grades[Number(event.detail.value)] })
   },