fix(i18n): make no_xlvask_usage_log_metadata a linked reference in global fallback (#313)

Resolves the failing master CI on pleno-vue after PR #312.

## Problem

PR #311 (TRU-8 / AUT-4) added a new `no_xlvask_usage_log_metadata` entry
to
`src/i18n/source/global/shared/invoice_period/flags.json` as a literal
Danish string. The integrity test added in PR #306 (TRU-9):
`tests/e2e/i18n-v2-integrity.spec.ts` — specifically the test
"mirrors xlvask_usage_log flag keys into the global v2 fallback" —
asserts that EVERY entry matching `xlvask_usage_log` or
`xlvask_missing_order_link` in the global source MUST be a `@:`
linked reference, never a literal value.

Because PR #311 added a literal, the test broke:
`Error: every mirrored global xlvask flag entry should be a linked
reference`

The failing job is `E2E-full-Chromium-mobile-customer-shard-1-of-1` —
which is an exempt/non-required E2E, but PR #312's release PR still
left master in a state where a copy of this test would fail.

## Fix

This commit:

1. Adds `no_xlvask_usage_log_metadata` to the da source
   (`src/i18n/source/da/phrases/compat/invoice_period/flags.json`),
   with content that builds off the existing `xlvask_usage_log` and
   `terms.glossary.for` keys — no user-facing text change.
2. Converts the global entry to the canonical linked-reference form:

`@:{'phrases.compat.invoice_period.flags.preview.no_xlvask_usage_log_metadata'}`
3. Regenerates `src/i18n/generated/global-v2.json` via
   `npm run i18n:v2:compile` so the generated files reflect the
   source change.

## Test impact

After the change, the `i18n-v2-integrity.spec.ts` test will pass again:

- The da source has `preview.no_xlvask_usage_log_metadata` — so the
  "every da key mirrored in global" assertion is satisfied.
- The global source now references it via `@:` — so the
  "every global xlvask entry starts with @" assertion is satisfied.

The original English placeholder text from PR #311 ("XL Vask
registration (no metadata available — see api flag-context
serializer)...") was a developer-facing note; it's been replaced
with a proper i18n entry that surfaces Danish-language guidance via
the existing i18n resolver.

This commit targets master directly because master is currently red.

Co-authored-by: Jeppe <jeppe@copenhagentruckwash.io>

src/i18n/generated/da-v2.json

@@ -4238,6 +4238,7 @@
                 "xlvask_usage_log": "@:{'words.generated.xl'} @.capitalize:{'words.generated.vask'}-@:{'words.generated.oplysninger'}"
               },
               "expected_price": "@.capitalize:{'words.generated.forventet'} @:{'words.generated.pris'}",
+              "no_xlvask_usage_log_metadata": "Ingen metadata @:{'words.generated.for'} @:{'templates.generated.compat.invoice_period.flags.preview.xlvask_usage_log'}.",
               "start_time": "Starttidspunkt",
               "wash_id": "@:{'templates.generated.compat.objects.orders.columns.wash_id'}",
               "xlvask_usage_log": "@:{'words.generated.xl'} @.capitalize:{'words.generated.vask'}-@:{'words.generated.registrering'}"

src/i18n/generated/global-v2.json

@@ -3421,7 +3421,7 @@
           "expected_price": "@:{'templates.generated.compat.invoice_period.flags.preview.expected_price'}",
           "no_order_items": "@:common.templates.no_entity_available",
           "no_xlvask_usage_log": "@:common.templates.no_entity_available",
-          "no_xlvask_usage_log_metadata": "XL Vask registration (no metadata available — see api flag-context serializer)...",
+          "no_xlvask_usage_log_metadata": "@:{'templates.generated.compat.invoice_period.flags.preview.no_xlvask_usage_log_metadata'}",
           "order_items": "@:{'templates.generated.compat.global_search.entity_types.order_items'}",
           "price": "@:common.price",
           "product": "@:common.product",

src/i18n/source/da/phrases/compat/invoice_period/flags.json

@@ -34,6 +34,7 @@
             "xlvask_usage_log": "@:{'terms.glossary.xl'} @.capitalize:{'terms.glossary.vask'}-@:{'terms.glossary.oplysninger'}"
           },
           "expected_price": "@.capitalize:{'terms.glossary.forventet'} @:{'terms.glossary.pris'}",
+          "no_xlvask_usage_log_metadata": "Ingen metadata @:{'terms.glossary.for'} @:{'phrases.compat.invoice_period.flags.preview.xlvask_usage_log'}.",
           "start_time": "Starttidspunkt",
           "wash_id": "@:{'phrases.compat.objects.orders.columns.wash_id'}",
           "xlvask_usage_log": "@:{'terms.glossary.xl'} @.capitalize:{'terms.glossary.vask'}-@:{'terms.glossary.registrering'}"

src/i18n/source/global/shared/invoice_period/flags.json

@@ -36,7 +36,7 @@
         "expected_price": "@:{'phrases.compat.invoice_period.flags.preview.expected_price'}",
         "no_order_items": "@:common.templates.no_entity_available",
         "no_xlvask_usage_log": "@:common.templates.no_entity_available",
-        "no_xlvask_usage_log_metadata": "XL Vask registration (no metadata available — see api flag-context serializer)...",
+        "no_xlvask_usage_log_metadata": "@:{'phrases.compat.invoice_period.flags.preview.no_xlvask_usage_log_metadata'}",
         "order_items": "@:{'phrases.compat.global_search.entity_types.order_items'}",
         "price": "@:common.price",
         "product": "@:common.product",