Remove unused NetworkType::Trojan tombstone

The Trojan network type only ever existed as a non-runnable tombstone:
the SOCKS-era Trojan runtime it guarded against (BEP-0009) was never
merged to main, and no stored network uses it. Drop the enum value and
its dead match arms across the daemon, GTK summary, and Apple bindings.

The Trojan *protocol* outbound used by proxy-subscription nodes
(TrojanOutbound / ProxyOutbound::Trojan / isTrojanTCP) is unaffected.

- proto: remove `Trojan = 2`, add `reserved 2; reserved "Trojan";`
- daemon: drop ResolvedTunnel/ActiveTunnel::Trojan variants + match arms
  (runtime.rs) and the validate_network_payload arm (database.rs)
- gtk: drop the "Legacy Trojan Proxy" summary arm
- apple: drop the makeCard .trojan arm and regenerate the Swift
  NetworkType enum (case/rawValue/init/allCases/nameMap)

An unknown stored type now surfaces via the existing UNRECOGNIZED path.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Apple/Core/Client/Generated/burrow.pb.swift

@@ -25,7 +25,6 @@ public enum Burrow_NetworkType: SwiftProtobuf.Enum, Swift.CaseIterable {
   public typealias RawValue = Int
   case wireGuard // = 0
   case tailnet // = 1
-  case trojan // = 2
   case proxySubscription // = 3
   case UNRECOGNIZED(Int)
 
@@ -37,7 +36,6 @@ public enum Burrow_NetworkType: SwiftProtobuf.Enum, Swift.CaseIterable {
     switch rawValue {
     case 0: self = .wireGuard
     case 1: self = .tailnet
-    case 2: self = .trojan
     case 3: self = .proxySubscription
     default: self = .UNRECOGNIZED(rawValue)
     }
@@ -47,7 +45,6 @@ public enum Burrow_NetworkType: SwiftProtobuf.Enum, Swift.CaseIterable {
     switch self {
     case .wireGuard: return 0
     case .tailnet: return 1
-    case .trojan: return 2
     case .proxySubscription: return 3
     case .UNRECOGNIZED(let i): return i
     }
@@ -57,7 +54,6 @@ public enum Burrow_NetworkType: SwiftProtobuf.Enum, Swift.CaseIterable {
   public static let allCases: [Burrow_NetworkType] = [
     .wireGuard,
     .tailnet,
-    .trojan,
     .proxySubscription,
   ]
 
@@ -246,7 +242,6 @@ extension Burrow_NetworkType: SwiftProtobuf._ProtoNameProviding {
   public static let _protobuf_nameMap: SwiftProtobuf._NameMap = [
     0: .same(proto: "WireGuard"),
     1: .same(proto: "Tailnet"),
-    2: .same(proto: "Trojan"),
     3: .same(proto: "ProxySubscription"),
   ]
 }