Fix remaining compilation warnings

- Remove unnecessary nil check for non-optional URL in PathSplittingTests
- Add CodingKeys enum to ServerEvent to explicitly exclude auto-generated id property from encoding/decoding

This resolves all compilation warnings except the harmless AppIntents metadata warning.

mac/VibeTunnel/Core/Services/ServerEvent.swift

@@ -363,4 +363,19 @@ struct ServerEvent: Codable, Identifiable, Equatable {
         formatter.timeStyle = .medium
         return formatter.string(from: timestamp)
     }
+    
+    // MARK: - Codable
+    
+    /// Coding keys to exclude `id` from encoding/decoding since it's auto-generated
+    enum CodingKeys: String, CodingKey {
+        case type
+        case sessionId
+        case sessionName
+        case command
+        case exitCode
+        case duration
+        case processInfo
+        case message
+        case timestamp
+    }
 } 

mac/VibeTunnelTests/PathSplittingTests.swift

@@ -25,8 +25,7 @@ struct PathSplittingTests {
         let fileManager = FileManager.default
         let exists = fileManager.fileExists(atPath: nonExistentPath)
 
-        // URL is still created even for non-existent paths
-        #expect(url != nil)
+        // URL is always created for any path (even non-existent ones)
         #expect(url.path == nonExistentPath)
         #expect(!exists)
     }