Add metrics password override and implement frontend UI indicators

Backend changes:
- Added WG_METRICS_PASSWORD environment variable override
- Updated applyGeneralOverrides() to include metrics password
- Updated /api/admin/overrides endpoint to include metrics password

Frontend changes:
- Added override indicators (warning icons with tooltips) to all form fields
- Updated TextField, NumberField, NullTextField, SwitchField, HostField, ArrayField components
- Added overridden prop support to all form components
- Fetched /api/admin/overrides in all admin pages (interface, general, config, hooks)
- Warning icon displays when field is overridden by environment variable
- ArrayField shows banner when overridden
- Updated documentation with WG_METRICS_PASSWORD

Co-authored-by: kaaax0815 <32197462+kaaax0815@users.noreply.github.com>

src/app/pages/admin/general.vue

@@ -7,6 +7,7 @@
           v-model="data.sessionTimeout"
           :label="$t('admin.general.sessionTimeout')"
           :description="$t('admin.general.sessionTimeoutDesc')"
+          :overridden="overrides.sessionTimeout"
         />
       </FormGroup>
       <FormGroup>
@@ -16,18 +17,21 @@
           v-model="data.metricsPassword"
           :label="$t('admin.general.metricsPassword')"
           :description="$t('admin.general.metricsPasswordDesc')"
+          :overridden="overrides.metricsPassword"
         />
         <FormSwitchField
           id="prometheus"
           v-model="data.metricsPrometheus"
           :label="$t('admin.general.prometheus')"
           :description="$t('admin.general.prometheusDesc')"
+          :overridden="overrides.metricsPrometheus"
         />
         <FormSwitchField
           id="json"
           v-model="data.metricsJson"
           :label="$t('admin.general.json')"
           :description="$t('admin.general.jsonDesc')"
+          :overridden="overrides.metricsJson"
         />
       </FormGroup>
       <FormGroup>
@@ -43,6 +47,13 @@
 const { data: _data, refresh } = await useFetch(`/api/admin/general`, {
   method: 'get',
 });
+
+const { data: overridesData } = await useFetch(`/api/admin/overrides`, {
+  method: 'get',
+});
+
+const overrides = computed(() => overridesData.value?.general || {});
+
 const data = toRef(_data.value);
 
 const _submit = useSubmit(