Rename solar integration types to VotronicSolarESP

Renames every type and identifier we built for the solar charge
controller bridge from generic "Solar" naming to the product name
VotronicSolarESP: VanAlignSolarProtocol -> VotronicSolarESPProtocol,
SolarSession -> VotronicSolarESPSession, SolarState ->
VotronicSolarESPState, plus the dependent properties, parameters, and
user-facing discovery/empty-state strings.

Purely a Swift-side rename - the underlying BLE service/characteristic
UUIDs are untouched, so it has no effect on communicating with the
actual firmware. DeviceRole.solar's case name, and DemoData's device
instance variables, are left as-is since they describe the role/demo
device rather than this specific integration code.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

CamperMonitor/Store/DemoData.swift

@@ -81,8 +81,8 @@ enum DemoData {
     }
 
     /// Mittags, gute Sonne.
-    static var solarState: SolarState {
-        var state = SolarState()
+    static var votronicSolarESPState: VotronicSolarESPState {
+        var state = VotronicSolarESPState()
         state.batteryVoltage = 13.9
         state.pvVoltage = 19.4
         state.pvCurrent = 6.2
@@ -96,7 +96,7 @@ enum DemoData {
 
     /// Ein paar Stunden Verlauf je Kanal, damit die Grafik im Demo-Modus
     /// sofort etwas zeigt statt erst nach ein paar Minuten Laufzeit.
-    static func solarHistory() -> DeviceHistory {
+    static func votronicSolarESPHistory() -> DeviceHistory {
         let now = Date()
         func series(around value: Double, noise: Double) -> [HistorySample] {
             (0..<120).reversed().map { step in