add fixture-invoicing example, sample-room wrap, kind cluster support

- examples/fixture-invoicing/: FastAPI + Vue + Postgres demo (4-entity invoice fixture)
- cfg/sample/: wraps the fixture (managed.repos points at examples/)
- ctrl/kind-{up,down,status}.sh + per-room k8s render in soleprint/ctrl/k8s/
- build.py: relative repo paths, resilient rmtree, optional k8s render hook
- cfg/.gitignore: stop ignoring sample/ and standalone/ template rooms

Manifests render cleanly but kind cluster has not been run end-to-end yet.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

examples/fixture-invoicing/frontend/src/views/InvoiceDetail.vue

@@ -0,0 +1,148 @@
+<template>
+  <div v-if="invoice">
+    <h2>
+      Invoice {{ invoice.number }}
+      <span :class="['status', invoice.status]">{{ invoice.status }}</span>
+    </h2>
+    <p class="muted">
+      Customer: <strong>{{ invoice.customer.name }}</strong> ({{ invoice.customer.email }})
+      · Issued {{ invoice.issued_at?.slice(0, 10) }}
+      <span v-if="invoice.due_at"> · Due {{ invoice.due_at.slice(0, 10) }}</span>
+    </p>
+
+    <div class="card">
+      <h3>Line items</h3>
+      <table v-if="invoice.line_items.length">
+        <thead>
+          <tr>
+            <th>Description</th>
+            <th>Qty</th>
+            <th>Unit price</th>
+            <th>Total</th>
+            <th></th>
+          </tr>
+        </thead>
+        <tbody>
+          <tr v-for="li in invoice.line_items" :key="li.id">
+            <td>{{ li.description }}</td>
+            <td>{{ li.quantity }}</td>
+            <td>${{ li.unit_price }}</td>
+            <td>${{ (li.quantity * li.unit_price).toFixed(2) }}</td>
+            <td><button class="ghost" @click="removeLine(li.id)">Remove</button></td>
+          </tr>
+        </tbody>
+      </table>
+      <p v-else class="muted">No line items.</p>
+
+      <div class="actions" style="margin-top: 12px;">
+        <input v-model="lineDraft.description" placeholder="Description" />
+        <input type="number" v-model.number="lineDraft.quantity" style="width: 80px;" />
+        <input type="number" step="0.01" v-model.number="lineDraft.unit_price" style="width: 120px;" />
+        <button @click="addLine" :disabled="!lineDraft.description">Add line</button>
+      </div>
+    </div>
+
+    <div class="card">
+      <h3>Payments</h3>
+      <table v-if="invoice.payments.length">
+        <thead>
+          <tr>
+            <th>Amount</th>
+            <th>Method</th>
+            <th>Paid at</th>
+            <th></th>
+          </tr>
+        </thead>
+        <tbody>
+          <tr v-for="p in invoice.payments" :key="p.id">
+            <td>${{ p.amount }}</td>
+            <td>{{ p.method }}</td>
+            <td>{{ p.paid_at?.slice(0, 10) }}</td>
+            <td><button class="ghost" @click="removePayment(p.id)">Remove</button></td>
+          </tr>
+        </tbody>
+      </table>
+      <p v-else class="muted">No payments.</p>
+
+      <div class="actions" style="margin-top: 12px;">
+        <input type="number" step="0.01" v-model.number="payDraft.amount" placeholder="Amount" />
+        <select v-model="payDraft.method">
+          <option value="cash">cash</option>
+          <option value="card">card</option>
+          <option value="transfer">transfer</option>
+        </select>
+        <button @click="addPayment" :disabled="!payDraft.amount">Record payment</button>
+      </div>
+    </div>
+
+    <p class="muted">
+      Total billed: <strong>${{ totalBilled.toFixed(2) }}</strong>
+      · Total paid: <strong>${{ totalPaid.toFixed(2) }}</strong>
+      · Balance: <strong>${{ (totalBilled - totalPaid).toFixed(2) }}</strong>
+    </p>
+  </div>
+  <p v-else class="muted">Loading…</p>
+</template>
+
+<script setup>
+import { ref, reactive, computed, onMounted, watch } from "vue";
+import { api } from "../api.js";
+
+const props = defineProps({ id: { type: [String, Number], required: true } });
+
+const invoice = ref(null);
+const lineDraft = reactive({ description: "", quantity: 1, unit_price: 0 });
+const payDraft = reactive({ amount: 0, method: "cash" });
+
+const totalBilled = computed(() =>
+  (invoice.value?.line_items || []).reduce(
+    (sum, li) => sum + Number(li.quantity) * Number(li.unit_price), 0
+  )
+);
+const totalPaid = computed(() =>
+  (invoice.value?.payments || []).reduce(
+    (sum, p) => sum + Number(p.amount), 0
+  )
+);
+
+async function load() {
+  invoice.value = await api.getInvoice(props.id);
+}
+
+async function addLine() {
+  await api.addLineItem(props.id, { ...lineDraft });
+  lineDraft.description = "";
+  lineDraft.quantity = 1;
+  lineDraft.unit_price = 0;
+  await load();
+}
+
+async function removeLine(id) {
+  await api.deleteLineItem(id);
+  await load();
+}
+
+async function addPayment() {
+  await api.recordPayment(props.id, { ...payDraft });
+  payDraft.amount = 0;
+  await load();
+}
+
+async function removePayment(id) {
+  await api.deletePayment(id);
+  await load();
+}
+
+watch(() => props.id, load);
+onMounted(load);
+</script>
+
+<style scoped>
+.actions input, .actions select {
+  padding: 8px 10px;
+  border: 1px solid #334;
+  border-radius: 4px;
+  background: #0d1b2a;
+  color: var(--text);
+}
+</style>