Add OCPP control for the Anker Solix EV charger (Own/Proxy CSMS)

The Anker Solix connector was read-only (cloud monitoring only). Add an
OCPP 1.6J control path with a per-user, cascading control mode:

  - off   monitoring only (default, unchanged behavior)
  - own   DriverVault is the charger's Central System (full control)
  - proxy DriverVault relays to Anker's cloud and injects commands

New internal/ocpp subsystem (stdlib-only, hand-rolled RFC 6455): a CSMS
with session management, inbound dispatch, and typed control commands
(RemoteStart/Stop, SetChargingProfile current limit, ChangeAvailability,
Reset, UnlockConnector, TriggerMessage, Get/ChangeConfiguration). Own- and
proxy-mode paths are verified end-to-end against a simulated charge point.

The charger connects to /ocpp/{serial}, authenticated with OCPP Basic auth
(serial + a per-charger control token) resolved to the owning user via an
in-memory token index. Control REST endpoints mirror the monitoring ones and
reuse the same cascade gate plus a live-session check. controlMode is a new
cascade field (global -> org -> user) advertised as a select on the plugin.

Frontend: control-mode select + provisioning card in Settings, and a real
Start/Stop/limit/reset control panel in Charging, gated on the active mode.

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

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

@@ -47,6 +47,22 @@
       "idle": "Not charging",
       "idleHint": "Plug in at a station to start a session."
     },
+    "control": {
+      "title": "Charger control",
+      "connected": "Connected",
+      "disconnected": "Offline",
+      "serialPlaceholder": "Charger serial (e.g. A5191-XXXXXXXX)",
+      "refresh": "Refresh",
+      "status": "Connector",
+      "meter": "Energy",
+      "start": "Start charging",
+      "stop": "Stop charging",
+      "limit": "Current limit",
+      "applyLimit": "Apply limit",
+      "clearLimit": "Clear limit",
+      "reset": "Reset charger",
+      "connectHint": "Enter your charger's serial and refresh. The charger must be connected to DriverVault's OCPP backend (set up in Settings → Integrations)."
+    },
     "stations": {
       "heading": "Nearby",
       "count": {
@@ -222,7 +238,23 @@
       "ankerEmail": "Anker account email",
       "ankerPassword": "Anker account password",
       "country": "Country",
-      "countryHint": "Two-letter country code of your Anker account (e.g. DE, GB, US)."
+      "countryHint": "Two-letter country code of your Anker account (e.g. DE, GB, US).",
+      "controlMode": "Control mode",
+      "controlModeHint": "How DriverVault controls the charger over OCPP.",
+      "controlOff": "Off (monitoring only)",
+      "controlOwn": "Own CSMS (full control)",
+      "controlProxy": "Proxy CSMS (relay + control)",
+      "controlTitle": "Charger control (OCPP)",
+      "controlOwnHint": "The charger connects directly to DriverVault as its Central System. Point the charger's OCPP backend at the endpoint below.",
+      "controlProxyHint": "DriverVault relays to Anker's cloud and can inject commands. Point the charger's OCPP backend at the endpoint below.",
+      "controlProvisionSteps": "In the Anker app (or the charger's OCPP settings), set the OCPP backend URL to the endpoint and the authorization key to the token above.",
+      "chargerSerial": "Charger serial",
+      "controlCheck": "Check status",
+      "controlGenerate": "Generate token",
+      "controlEndpoint": "OCPP endpoint",
+      "controlToken": "Auth token",
+      "controlConnected": "Connected to control backend",
+      "controlDisconnected": "Not connected"
     },
 
     "privacy": {