Make version field in config mandatory and remove fallback logic

This commit aligns with the decision to drop support for configurations without a version field (pre-0.3.0). The `version` property in `Config` is now non-optional and must be explicitly set at creation.

- Removed the fallback assignment to "0.3.0"
- Updated all code to require and use non-optional `version`
- Adjusted the config initializer to take `version` as a parameter
- Simplified conditional checks and eliminated `.version?`

This ensures that swiftly no longer silently accepts or upgrades legacy configurations without an explicit version.

Author: belkhadir

Sources/Swiftly/Config.swift

@@ -9,12 +9,13 @@ public struct Config: Codable, Equatable, Sendable {
     public var inUse: ToolchainVersion?
     public var installedToolchains: Set<ToolchainVersion>
     public var platform: PlatformDefinition
-    public var version: SwiftlyVersion?
+    public var version: SwiftlyVersion
 
-    init(inUse: ToolchainVersion?, installedToolchains: Set<ToolchainVersion>, platform: PlatformDefinition) {
+    init(inUse: ToolchainVersion?, installedToolchains: Set<ToolchainVersion>, platform: PlatformDefinition, version: SwiftlyVersion) {
         self.inUse = inUse
         self.installedToolchains = installedToolchains
         self.platform = platform
+        self.version = version
     }
 
     private static func makeEncoder() -> JSONEncoder {
@@ -28,12 +29,8 @@ public struct Config: Codable, Equatable, Sendable {
         do {
             let configFile = Swiftly.currentPlatform.swiftlyConfigFile(ctx)
             let data = try await fs.cat(atPath: configFile)
-            var config = try JSONDecoder().decode(Config.self, from: data)
-            if config.version == nil {
-                // Assume that the version of swiftly is 0.3.0 because that is the last
-                // unversioned release.
-                config.version = SwiftlyCore.version
-            }
+            let config = try JSONDecoder().decode(Config.self, from: data)
+
             return config
         } catch {
             let msg = """

Sources/Swiftly/Init.swift

@@ -48,7 +48,7 @@ struct Init: SwiftlyCommand {
             (
                 config.version == SwiftlyVersion(major: 0, minor: 4, patch: 0, suffix: "dev") ||
                     config.version == SwiftlyVersion(major: 0, minor: 4, patch: 0) ||
-                    (config.version?.major == 1 && config.version?.minor == 0)
+                    (config.version.major == 1 && config.version.minor == 0)
             )
         {
             // This is a simple upgrade from the 0.4.0 pre-releases, or 1.x
@@ -178,9 +178,8 @@ struct Init: SwiftlyCommand {
         // Force the configuration to be present. Generate it if it doesn't already exist or overwrite is set
         if overwrite || config == nil {
             let pd = try await Swiftly.currentPlatform.detectPlatform(ctx, disableConfirmation: assumeYes, platform: platform)
-            var c = Config(inUse: nil, installedToolchains: [], platform: pd)
-            // Stamp the current version of swiftly on this config
-            c.version = SwiftlyCore.version
+            let c = Config(inUse: nil, installedToolchains: [], platform: pd, version: SwiftlyCore.version)
+            
             try c.save(ctx)
             config = c
         }