App 2.12.0, server 2.5.0: enter settings on the phone

The ABRP credentials are long to type on the car. "Enter on phone"
(Live data tab, and Settings next to the charging price) shows a QR
code; it opens a form on the server where the phone sends the ABRP API
key and user token, charging price and usable capacity, confirmed with
the approval password. The car polls with its own token and collects
the values once, then saves them through the same checks as the fields
on screen.

Same device-flow shape as pairing. The server keeps the values in memory
only, at most ten minutes, hands them out once with no-store, and never
logs them or puts them back into the page; a paired token only reaches
its own installation's request. Pairing's QR dialog is now shared
(PhoneQrDialog), and the phone pages share one stylesheet.

The config file also takes charging_price and usable_kwh.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QLJfZQZeAKAwSqViTmLzki

server/api.go

@@ -18,6 +18,7 @@ import (
 //	PUT  /v1/charging-sessions/{sessionId}       one finished DC charging session
 //	GET  /v1/consumption/history/{installationId} the car reads its own totals back
 //	GET  /v1/health                              unauthenticated liveness probe
+//	     /v1/settings/…, /settings                settings typed on a phone (handoff_http.go)
 //
 // A car authenticates with the shared INGEST_TOKEN or with its own token from pairing
 // (pairing_http.go).
@@ -25,6 +26,8 @@ type API struct {
 	Store       Store
 	IngestToken string
 	Pairing     *Pairing
+	// Handoff carries settings typed on a phone to the car (handoff.go).
+	Handoff *Handoff
 	// PublicURL is the server's address as a phone reaches it, for the pairing QR code;
 	// derived from the request when empty.
 	PublicURL string
@@ -42,6 +45,7 @@ func (a *API) Routes() http.Handler {
 	mux.HandleFunc("PUT /v1/charging-sessions/{sessionId}", a.ingest(a.chargingSession))
 	mux.HandleFunc("GET /v1/consumption/history/{installationId}", a.ingest(a.history))
 	a.pairingRoutes(mux)
+	a.handoffRoutes(mux)
 	return mux
 }