Explain Kiro CLI requirement when no fetch strategy is available

Sources/CodexBarCore/Providers/ProviderFetchPlan.swift

@@ -175,7 +175,10 @@ public enum ProviderFetchError: LocalizedError, Sendable {
     public var errorDescription: String? {
         switch self {
         case let .noAvailableStrategy(provider):
-            "No available fetch strategy for \(provider.rawValue)."
+            if provider == .kiro {
+                return "Kiro usage requires the Kiro CLI. Install it from https://kiro.dev/docs/cli/ and run 'kiro-cli login' first."
+            }
+            return "No available fetch strategy for \(provider.rawValue)."
         }
     }
 }

Tests/CodexBarTests/ProviderFetchErrorTests.swift

@@ -0,0 +1,12 @@
+import Testing
+@testable import CodexBarCore
+
+struct ProviderFetchErrorTests {
+    @Test
+    func `missing kiro strategy explains cli requirement`() {
+        let message = ProviderFetchError.noAvailableStrategy(.kiro).localizedDescription
+
+        #expect(message.contains("Kiro CLI"))
+        #expect(message.contains("kiro-cli login"))
+    }
+}