fix(campaigns): preview and review steps showed empty values

Form.useWatch([], form) tracks getFieldsValue(), which returns {} on a step
with no mounted Form.Item. The Preview and Review steps have none, so on
entering Preview the creative memo recomputed to empty and previewed a blank
ad pointing at example.com, and the Review step rendered "-" for every field.
The submitted payload was always correct — submit() reads the preserved store
via getFieldsValue(true) — so this was a display and preview defect, not data
loss. Pass preserve: true so the watch tracks the whole store.

Also document VITE_META_AD_ACCOUNT_ID. Unset, it silently disables the
billing panel, the missing-payment-method warning, ad preview, and the
account-minimum budget check, with no diagnostic anywhere.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.env.development.example

@@ -1,2 +1,7 @@
 VITE_MASKANX_API_URL=https://api-dev.example.com
 VITE_MASKANX_PROXY_TARGET=http://127.0.0.1:8088
+
+# Meta ad account used by the Campaigns page (act_<id>).
+# Without it the billing panel, the "no payment method" warning, ad preview,
+# and the account-minimum budget check are all silently unavailable.
+VITE_META_AD_ACCOUNT_ID=

.env.example

@@ -1,2 +1,7 @@
 VITE_MASKANX_API_URL=http://127.0.0.1:8088
 VITE_MASKANX_PROXY_TARGET=http://127.0.0.1:8088
+
+# Meta ad account used by the Campaigns page (act_<id>).
+# Without it the billing panel, the "no payment method" warning, ad preview,
+# and the account-minimum budget check are all silently unavailable.
+VITE_META_AD_ACCOUNT_ID=

.env.local.example

@@ -1,3 +1,8 @@
 # Leave the public URL empty to use the Vite /api proxy locally.
 VITE_MASKANX_API_URL=
 VITE_MASKANX_PROXY_TARGET=http://127.0.0.1:8088
+
+# Meta ad account used by the Campaigns page (act_<id>).
+# Without it the billing panel, the "no payment method" warning, ad preview,
+# and the account-minimum budget check are all silently unavailable.
+VITE_META_AD_ACCOUNT_ID=

.env.production.example

@@ -1 +1,6 @@
 VITE_MASKANX_API_URL=https://api.maskanx.example.com
+
+# Meta ad account used by the Campaigns page (act_<id>).
+# Without it the billing panel, the "no payment method" warning, ad preview,
+# and the account-minimum budget check are all silently unavailable.
+VITE_META_AD_ACCOUNT_ID=

.env.testing.example

@@ -1,2 +1,7 @@
 VITE_MASKANX_API_URL=http://127.0.0.1:8089
 VITE_MASKANX_PROXY_TARGET=http://127.0.0.1:8089
+
+# Meta ad account used by the Campaigns page (act_<id>).
+# Without it the billing panel, the "no payment method" warning, ad preview,
+# and the account-minimum budget check are all silently unavailable.
+VITE_META_AD_ACCOUNT_ID=

README.md

@@ -19,6 +19,20 @@ npm run local
 
 Start `maskanx-backend` on port `8088` before using the full UI.
 
+## Campaigns page
+
+The Campaigns page needs `VITE_META_AD_ACCOUNT_ID` set to the Meta ad account
+id (`act_<digits>`) in your `.env.*` file.
+
+If it is unset the page still loads and lists campaigns, but four things are
+silently unavailable: the ad-account billing panel, the warning shown when no
+payment method is attached, ad preview in the wizard, and the account-minimum
+budget check (the backend cannot look up `min_daily_budget` without an
+account, so it skips that validation and logs a warning).
+
+Ad preview also requires `META_ADS_ACCESS_TOKEN` to be configured on the
+backend, in Settings > Environments.
+
 ## Commands
 
 | Command | Purpose |

src/pages/Campaigns/CampaignWizard.tsx

@@ -74,7 +74,12 @@ export default function CampaignWizard({
   const [step, setStep] = useState(0);
   const [saving, setSaving] = useState(false);
 
-  const values: WizardValues = Form.useWatch([], form) ?? EMPTY_VALUES;
+  // `preserve: true` is required. Only the active step is mounted, so a bare
+  // useWatch tracks getFieldsValue() — which returns {} on a step with no
+  // Form.Item (Preview, Review). Without this the Preview step would render a
+  // blank creative and the Review step would show "-" for every field.
+  const values: WizardValues =
+    Form.useWatch([], { form, preserve: true }) ?? EMPTY_VALUES;
 
   // Memoised so PreviewStep's effect does not refire on every parent render.
   const creative = useMemo(