Wire the Anker Solix EV charger into the per-user integration cascade

Expose the anker-solix plugin to end users the same way as Toyota: a
global -> org -> user settings cascade so everyone can run it under their
own Anker account, with a superadmin (and org admin) able to impose
settings from above.

API Server: integrations_ankersolix.go mirrors integrations.go with the
Anker fields (email + password resolve as a pair from the highest layer,
country resolves on its own), plus GET/PUT/health/chargers routes under
/api/integrations/anker-solix. Secrets and inherited emails are masked;
the live probe runs server-side under the resolved credentials.

Web App: api.js client calls, a second Integrations card in Settings.vue
(scope switch, enable toggle, email/password/country with locked-field
inheritance notes, save + test), and the en.json strings.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Web App/web/src/i18n/en.json

@@ -187,7 +187,13 @@
       "save": "Save",
       "saved": "Saved ✓",
       "connected": "Connected",
-      "notConnected": "Not connected"
+      "notConnected": "Not connected",
+      "ankerSolix": "Anker Solix (V1 Smart EV Charger)",
+      "ankerSolixDesc": "Sign in with your Anker account to pull EV charger data from the Anker Solix cloud.",
+      "ankerEmail": "Anker account email",
+      "ankerPassword": "Anker account password",
+      "country": "Country",
+      "countryHint": "Two-letter country code of your Anker account (e.g. DE, GB, US)."
     },
 
     "privacy": {