Server: rewrite in Go as an API-only service

Same endpoints, request formats, validation rules and InfluxDB layout as
the Next.js server, so the car needs no change: POST /v1/telemetry,
PUT /v1/consumption/daily, PUT /v1/charging-sessions/{id}, GET
/v1/consumption/history/{id}, GET /v1/health. The dashboard, login and
the /v1/history reads are gone; Grafana takes over the dashboards.

- Go 1.26 standard library (net/http routing, log/slog) plus the
  official InfluxDB 2 client. Fails closed at startup on a missing
  InfluxDB setting or an ingest token under 24 characters.
- ABRP forwarder ported: newest fresh sample, rate limited, never
  queued, credentials only in the form body.
- 22 tests: validation, aggregation, forwarding, config, and the
  handlers through a fake store. govulncheck clean (x/net 0.60.0,
  toolchain go1.26.9).
- Image: static binary on distroless, about 11 MB, UID 65532, port
  8080; the build runs vet and the tests.
- Dev shell: Go, gopls and govulncheck instead of Node.

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

server/model.go

@@ -0,0 +1,108 @@
+package main
+
+import "time"
+
+// Totals are one day's (or one chunk's) consumption counters.
+type Totals struct {
+	Km      float64 `json:"km"`
+	Kwh     float64 `json:"kwh"`
+	Hours   float64 `json:"hours"`
+	SocDrop float64 `json:"socDrop"`
+}
+
+func (t *Totals) add(o Totals) {
+	t.Km += o.Km
+	t.Kwh += o.Kwh
+	t.Hours += o.Hours
+	t.SocDrop += o.SocDrop
+}
+
+// ConsumptionChunk is one 2-minute delta of a day's consumption, as the car sends it.
+// Days are built from these when history is read.
+type ConsumptionChunk struct {
+	InstallationID string
+	Date           string // the car's local date, YYYY-MM-DD
+	RecordedAt     time.Time
+	Day            Totals
+	SohPercent     *float64
+}
+
+// DailyConsumption is a day folded from its chunks.
+type DailyConsumption struct {
+	InstallationID string    `json:"installationId"`
+	Date           string    `json:"date"`
+	RecordedAt     time.Time `json:"recordedAt"`
+	Day            Totals    `json:"day"`
+	SohPercent     *float64  `json:"sohPercent,omitempty"`
+	// Lifetime is the running total up to and including this day; not part of the
+	// car's history response, which carries one lifetime for all days.
+	Lifetime Totals `json:"-"`
+}
+
+type CurvePoint struct {
+	Timestamp  time.Time
+	PowerKw    float64
+	SocPercent *float64
+}
+
+type ChargingSession struct {
+	InstallationID      string
+	SessionID           string
+	StartedAt           time.Time
+	EndedAt             time.Time
+	DurationSeconds     float64
+	EnergyKwh           float64
+	ChargingLossPercent float64
+	GridEnergyKwh       float64
+	PricePerKwh         float64
+	TotalCost           float64
+	IsDemo              bool
+	StartSocPercent     *float64
+	EndSocPercent       *float64
+	Curve               []CurvePoint
+}
+
+// telemetryNumbers are the numeric live fields, named and unit-ed as ABRP's tlm/send
+// expects them, with the range each one must fall in.
+var telemetryNumbers = map[string][2]float64{
+	"soc":               {0, 100},        // %
+	"speed":             {0, 400},        // km/h
+	"power":             {-1000, 1000},   // kW, positive leaving the battery
+	"est_battery_range": {0, 2000},       // km
+	"capacity":          {0, 500},        // kWh
+	"soe":               {0, 500},        // kWh
+	"soh":               {0, 100},        // %
+	"kwh_charged":       {0, 1000},       // kWh, this charge session
+	"odometer":          {0, 10_000_000}, // km
+	"lat":               {-90, 90},       // °
+	"lon":               {-180, 180},     // °
+	"elevation":         {-1000, 10_000}, // m
+	"heading":           {0, 360},        // °
+	"batt_temp":         {-60, 100},      // °C
+	"cabin_temp":        {-60, 100},      // °C
+	"ext_temp":          {-60, 70},       // °C
+	"hvac_setpoint":     {0, 40},         // °C
+	"hvac_power":        {0, 50},         // kW
+	"voltage":           {0, 1500},       // V
+	"current":           {-2000, 2000},   // A
+	"tire_pressure_fl":  {0, 1000},       // kPa
+	"tire_pressure_fr":  {0, 1000},       // kPa
+	"tire_pressure_rl":  {0, 1000},       // kPa
+	"tire_pressure_rr":  {0, 1000},       // kPa
+}
+
+// telemetryFlags are the boolean live fields; ABRP takes them as 0/1.
+var telemetryFlags = []string{"is_charging", "is_dcfc", "is_parked"}
+
+// TelemetrySample is one live sample. Only UTC is always present; an unread signal is
+// absent from Numbers and Flags, never 0.
+type TelemetrySample struct {
+	UTC     int64 // epoch seconds
+	Numbers map[string]float64
+	Flags   map[string]bool
+}
+
+type TelemetryBatch struct {
+	InstallationID string
+	Samples        []TelemetrySample
+}