feat(electron): enhance feature execution with async prompt handling and authentication checks

- Updated the FeatureExecutor to wrap content blocks in an async generator for multimodal prompt compatibility.
- Added authentication checks in the ClaudeProvider to ensure proper API key or token availability, including loading from local CLI config.
- Improved error handling for missing authentication, providing clear console messages for user guidance.

This update enhances the robustness of feature execution and ensures proper authentication management for the Claude SDK.

app/electron/services/feature-executor.js

@@ -323,8 +323,18 @@ class FeatureExecutor {
           }
         }
 
-        // Use content blocks instead of plain text
-        prompt = contentBlocks;
+        // Wrap content blocks in async generator for SDK (required format for multimodal prompts)
+        prompt = (async function* () {
+          yield {
+            type: "user",
+            session_id: "",
+            message: {
+              role: "user",
+              content: contentBlocks,
+            },
+            parent_tool_use_id: null,
+          };
+        })();
       }
 
       // Planning: Analyze the codebase and create implementation plan
@@ -356,6 +366,15 @@ class FeatureExecutor {
       let currentQuery;
       isCodex = this.isCodexModel(feature);
 
+      // Ensure provider auth is available (especially for Claude SDK)
+      const provider = this.getProvider(feature);
+      if (provider?.ensureAuthEnv && !provider.ensureAuthEnv()) {
+        const authMsg =
+          "Missing Anthropic auth. Set ANTHROPIC_API_KEY or run `claude login` so ~/.claude/config.json contains oauth_token.";
+        console.error(`[FeatureExecutor] ${authMsg}`);
+        throw new Error(authMsg);
+      }
+
       // Validate that model string matches the provider
       if (isCodex) {
         // Ensure model string is actually a Codex model, not a Claude model
@@ -367,7 +386,6 @@ class FeatureExecutor {
         
         // Use Codex provider for OpenAI models
         console.log(`[FeatureExecutor] Using Codex provider for model: ${modelString}`);
-        const provider = this.getProvider(feature);
         currentQuery = provider.executeQuery({
           prompt,
           model: modelString,
@@ -712,8 +730,18 @@ class FeatureExecutor {
           }
         }
 
-        // Use content blocks instead of plain text
-        prompt = contentBlocks;
+        // Wrap content blocks in async generator for SDK (required format for multimodal prompts)
+        prompt = (async function* () {
+          yield {
+            type: "user",
+            session_id: "",
+            message: {
+              role: "user",
+              content: contentBlocks,
+            },
+            parent_tool_use_id: null,
+          };
+        })();
       }
 
       // Use appropriate provider based on model type