fix: update parent doc link field when nested Quick Edit Form

[the-narwhal]

Problem

When creating a new linked record from inside a Quick Edit Form (QEF) — for example, creating an Address while in the middle of creating a Customer on an invoice — the newly-created child record is silently never linked back to the parent.

Likely fixes #1487 too

Steps to reproduce:

1. Open a new Sales Invoice
2. Click the Customer field → Create a new customer
3. Inside the Customer QEF, click the Address field → Create a new address
4. Fill in and save the address
5. Save the customer

Result: The customer is saved without the address. No error is shown; the data is silently dropped.

---

Root Cause

Link.vue (and its siblings DynamicLink.vue, MultiLabelLink.vue) use the following pattern in openNewDoc():

const doc = fyo.doc.getNewDoc(schemaName, { name, ...filters });
openQuickEdit({ doc });

doc.once('afterSync', () => {
  this.$router.back();
  this.results = [];
  this.triggerChange(doc.name);   // relies on `this` being alive
});

openQuickEdit pushes a new route whose query changes the schemaName and name parameters. In Desk.vue the QEF component is keyed on exactly those values:

<component
  :is="Component"
  :key="route.query.schemaName + route.query.name"
/>

When the Address QEF opens, the key changes from "PartyNew Party 01" to "AddressNew Address 01", which destroys the Party QEF — and with it, the Link component whose this is closed over in the listener.

When the address is later saved and afterSync fires, triggerChange calls this.$emit('change', …). Vue 3 returns early from $emit when a component is unmounted (instance.isUnmounted guard), so the event never propagates, parentDoc.set() is never called, and the address field on the Party doc is never updated.

---

Fix

Capture parentDoc and fieldname before the navigation destroys the component, then directly call parentDoc.set() in the listener as a guaranteed fallback — regardless of whether the Link component is still alive:

const parentDoc = this.doc;
const fieldname = this.df.fieldname;

doc.once('afterSync', () => {
  this.$router.back();
  this.results = [];
  this.triggerChange(doc.name);
  // Directly set on the parent doc to handle the case where this
  // component has been unmounted (nested QEF scenario).
  if (parentDoc && fieldname) {
    parentDoc.set(fieldname, doc.name).catch(() => {});
  }
});

Because the parent doc is wrapped in Vue's reactive(), the recreated QEF instance (which gets the same cached doc object) will reactively reflect the updated field value without any extra wiring.

triggerChange is kept as well so the first-level case (non-nested QEF, where the component is still alive) continues to work exactly as before.

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Files Changed

File	Change
src/components/Controls/Link.vue	Capture parentDoc/fieldname; add direct parentDoc.set() call in afterSync listener
src/components/Controls/DynamicLink.vue	Same fix
src/components/Controls/MultiLabelLink.vue	Same fix