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/api.js

@@ -239,6 +239,20 @@ export const api = {
   saveAnkerSolix: (body) => request("/integrations/anker-solix", { method: "PUT", body: JSON.stringify(body) }),
   testAnkerSolix: () => request("/integrations/anker-solix/health", { method: "POST" }),
 
+  // Anker Solix OCPP control (per charger). getAnkerControl returns the control
+  // mode, connection status, provisioning endpoint + token, and a live status
+  // snapshot; ankerControlToken (re)generates the per-charger token the operator
+  // installs into the charger; ankerControlAction issues one OCPP command
+  // (start/stop/limit/clear-limit/availability/reset/unlock/trigger/config).
+  getAnkerControl: (sn) => request(`/integrations/anker-solix/chargers/${encodeURIComponent(sn)}/control`),
+  ankerControlToken: (sn) =>
+    request(`/integrations/anker-solix/chargers/${encodeURIComponent(sn)}/control/token`, { method: "POST" }),
+  ankerControlAction: (sn, action, body = {}) =>
+    request(`/integrations/anker-solix/chargers/${encodeURIComponent(sn)}/${action}`, {
+      method: "POST",
+      body: JSON.stringify(body),
+    }),
+
   // Settings — advanced / danger zone
   exportData: () => requestBlob("/me/export"),
   importData: (payload) => request("/me/import", { method: "POST", body: JSON.stringify(payload) }),