feat: wave 2 migration (P3, P5, P7 openspec changes)

Implements, verifies, and archives the three remaining Wave 2 changes from
openspec/MIGRATION-PLAN.md.

- add-wallet-settlement (P3): demo recharge, guarded withdrawal freeze and
  one-time admin review, paginated own fund entries, idempotent per-shop
  weekly/monthly settlement statements with commission rate and one-time
  payout confirmation.
- add-merchant-onboarding (P5): personal/enterprise applications with one live
  application per user, guarded review with mandatory rejection reason, and
  transactional shop + owner provisioning returning one-time credentials;
  mall onboarding/status pages and an admin review console.
- add-membership-messaging (P7): platform member levels, append-only growth
  accrual on order completion with guarded one-way leveling, order/shipment/
  refund system messages with unread/read state and soft deletion, plus the
  mall header unread badge.

Backend: migrations 0019-0023, new wallet, settlement, merchant_onboarding,
membership and messaging modules, event hooks in order/fulfillment/aftersale,
and integration suites for each. Shared contract extended and all three
frontends updated; code indexes, domain docs, backend guidelines and the
migration tracker synced.

Verification: cargo test -p vmall-api green twice consecutively; mall, admin
and shop-admin builds pass; browser smoke on every new surface; openspec
validate --all --strict green (33 passed).

The three changes share the @vmall/shared contract, the mall mock adapter and
per-app locale/nav files, so they are committed together to keep every commit
buildable.

apps/admin/components/MemberLevelForm.vue

@@ -0,0 +1,150 @@
+<script setup lang="ts">
+import { reactive, watch } from "vue";
+
+/**
+ * Bilingual create/edit form for one membership level. The draft object is the
+ * single editable surface; it reports the whole draft on change so the page owns
+ * draft persistence.
+ */
+interface LevelDraftFields {
+  nameEn: string;
+  nameZh: string;
+  icon: string;
+  growthThreshold: number;
+  benefitsEn: string;
+  benefitsZh: string;
+}
+
+const props = withDefaults(
+  defineProps<
+    LevelDraftFields & {
+      title: string;
+      /** Namespaces the test hooks so several forms can coexist on one page. */
+      scope: string;
+      hint?: string;
+      error?: string;
+      busy?: boolean;
+      submitLabel: string;
+    }
+  >(),
+  { hint: "", error: "", busy: false },
+);
+
+const emit = defineEmits<{
+  (e: "submit"): void;
+  (e: "change", value: LevelDraftFields): void;
+}>();
+
+// `type="number"` inputs hand back a string through v-model; normalize to the
+// contract's integer growth value when reporting the draft.
+const draft = reactive({
+  nameEn: props.nameEn,
+  nameZh: props.nameZh,
+  icon: props.icon,
+  growthThreshold: String(props.growthThreshold),
+  benefitsEn: props.benefitsEn,
+  benefitsZh: props.benefitsZh,
+});
+
+watch(
+  () => [
+    props.nameEn,
+    props.nameZh,
+    props.icon,
+    props.growthThreshold,
+    props.benefitsEn,
+    props.benefitsZh,
+  ],
+  () => {
+    draft.nameEn = props.nameEn;
+    draft.nameZh = props.nameZh;
+    draft.icon = props.icon;
+    draft.growthThreshold = String(props.growthThreshold);
+    draft.benefitsEn = props.benefitsEn;
+    draft.benefitsZh = props.benefitsZh;
+  },
+);
+
+watch(
+  draft,
+  () => {
+    emit("change", {
+      nameEn: draft.nameEn,
+      nameZh: draft.nameZh,
+      icon: draft.icon,
+      growthThreshold: Number(draft.growthThreshold),
+      benefitsEn: draft.benefitsEn,
+      benefitsZh: draft.benefitsZh,
+    });
+  },
+  { deep: true },
+);
+</script>
+
+<template>
+  <VPanel :title="props.title">
+    <p v-if="props.hint" class="text-muted mb-4 text-sm">{{ props.hint }}</p>
+    <div class="grid gap-3 md:grid-cols-3">
+      <VField :label="$t('admin.memberLevelNameEn')">
+        <VInput
+          v-model="draft.nameEn"
+          :data-testid="`ml-${props.scope}-name-en`"
+          required
+          :disabled="props.busy"
+        />
+      </VField>
+      <VField :label="$t('admin.memberLevelNameZh')">
+        <VInput
+          v-model="draft.nameZh"
+          :data-testid="`ml-${props.scope}-name-zh`"
+          required
+          :disabled="props.busy"
+        />
+      </VField>
+      <VField :label="$t('admin.memberLevelIcon')">
+        <VInput
+          v-model="draft.icon"
+          :data-testid="`ml-${props.scope}-icon`"
+          required
+          :disabled="props.busy"
+        />
+      </VField>
+      <VField :label="$t('admin.memberLevelGrowth')">
+        <VInput
+          v-model="draft.growthThreshold"
+          :data-testid="`ml-${props.scope}-growth`"
+          type="number"
+          min="0"
+          step="1"
+          required
+          :disabled="props.busy"
+        />
+      </VField>
+      <VField :label="$t('admin.memberLevelBenefitsEn')">
+        <VInput
+          v-model="draft.benefitsEn"
+          :data-testid="`ml-${props.scope}-benefits-en`"
+          required
+          :disabled="props.busy"
+        />
+      </VField>
+      <VField :label="$t('admin.memberLevelBenefitsZh')">
+        <VInput
+          v-model="draft.benefitsZh"
+          :data-testid="`ml-${props.scope}-benefits-zh`"
+          required
+          :disabled="props.busy"
+        />
+      </VField>
+    </div>
+    <p v-if="props.error" class="text-danger my-2 text-sm" role="alert">{{ props.error }}</p>
+    <VBtn
+      variant="primary"
+      :data-testid="`ml-${props.scope}-submit`"
+      :disabled="props.busy"
+      @click="emit('submit')"
+    >
+      {{ props.busy ? $t("common.loading") : props.submitLabel }}
+    </VBtn>
+  </VPanel>
+</template>