fix: auto-find Package.swift for SPM commands, fix VS Code git scanning

- XcodeTools: swift_package commands now search workspace root and
  immediate subdirs for Package.swift instead of blindly running
  from workspaceRoot (fixes 'Could not find Package.swift' error)
- VS Code: set git.autoRepositoryDetection=openEditors and
  git.scanRepositories=[] to prevent path-doubling on CxSwiftAgent

Agent/Tools/XcodeTools.swift

@@ -26,7 +26,10 @@ enum XcodeTools {
             ] as [String: Any]
         ) { args in
             if args["swift_package"] as? Bool == true {
-                return runCommand("swift", ["build"], in: config.workspaceRoot)
+                guard let spmDir = findPackageSwift(from: config.workspaceRoot) else {
+                    return err("Could not find Package.swift in workspace. Specify a project path or use xcode_build without swift_package.")
+                }
+                return runCommand("swift", ["build"], in: spmDir)
             }
             let xcArgs = buildXcodebuildCmd(args, action: "build", config: config)
             return runCommand(config.xcodePath, xcArgs, in: config.workspaceRoot)
@@ -48,7 +51,10 @@ enum XcodeTools {
             ] as [String: Any]
         ) { args in
             if args["swift_package"] as? Bool == true {
-                return runCommand("swift", ["test"], in: config.workspaceRoot)
+                guard let spmDir = findPackageSwift(from: config.workspaceRoot) else {
+                    return err("Could not find Package.swift in workspace. Specify a project path or use xcode_test without swift_package.")
+                }
+                return runCommand("swift", ["test"], in: spmDir)
             }
             var xcArgs = buildXcodebuildCmd(args, action: "test", config: config)
             if let plan = args["test_plan"] as? String {
@@ -141,7 +147,10 @@ enum XcodeTools {
             annotations: ToolAnnotations(destructiveHint: true)
         ) { args in
             if args["swift_package"] as? Bool == true {
-                return runCommand("swift", ["package", "clean"], in: config.workspaceRoot)
+                guard let spmDir = findPackageSwift(from: config.workspaceRoot) else {
+                    return err("Could not find Package.swift in workspace.")
+                }
+                return runCommand("swift", ["package", "clean"], in: spmDir)
             }
             let xcArgs = buildXcodebuildCmd(args, action: "clean", config: config)
             return runCommand(config.xcodePath, xcArgs, in: config.workspaceRoot)
@@ -215,6 +224,29 @@ enum XcodeTools {
 
     // MARK: - Helpers
 
+    /// Search for Package.swift in the root and one level of subdirectories.
+    private static func findPackageSwift(from root: String) -> String? {
+        let fm = FileManager.default
+        // Check root first
+        if fm.fileExists(atPath: (root as NSString).appendingPathComponent("Package.swift")) {
+            return root
+        }
+        // Check immediate subdirectories
+        if let children = try? fm.contentsOfDirectory(atPath: root) {
+            for child in children {
+                let childPath = (root as NSString).appendingPathComponent(child)
+                var isDir: ObjCBool = false
+                if fm.fileExists(atPath: childPath, isDirectory: &isDir), isDir.boolValue {
+                    let pkg = (childPath as NSString).appendingPathComponent("Package.swift")
+                    if fm.fileExists(atPath: pkg) {
+                        return childPath
+                    }
+                }
+            }
+        }
+        return nil
+    }
+
     private static func buildXcodebuildCmd(_ args: [String: Any], action: String, config: AgentConfig) -> [String] {
         var xcArgs = [action]