Fix all static analysis errors (golangci-lint)

- Fix errcheck: handle all error return values in production code
- Fix errcheck: handle all error return values in test files
- Fix staticcheck: replace deprecated WithCredentialsFile with WithAuthCredentialsFile
- Remove unused code: authHeaders, planToEatPlannerItem, planToEatResponse
- Use defer func() { _ = x.Close() }() pattern for ignored close errors

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/internal/api/todoist_test.go b/internal/api/todoist_test.go
index 2fa6e28..7bbcc1e 100644
--- a/internal/api/todoist_test.go
+++ b/internal/api/todoist_test.go
@@ -13,7 +13,7 @@ import (
 // newTestTodoistClient creates a TodoistClient for testing with custom base URL
 func newTestTodoistClient(baseURL, apiKey string) *TodoistClient {
 	client := NewTodoistClient(apiKey)
-	client.BaseClient.BaseURL = baseURL
+	client.BaseURL = baseURL
 	client.syncClient.BaseURL = baseURL
 	return client
 }
@@ -62,7 +62,7 @@ func TestTodoistClient_CreateTask(t *testing.T) {
 		}
 
 		w.Header().Set("Content-Type", "application/json")
-		json.NewEncoder(w).Encode(response)
+		_ = json.NewEncoder(w).Encode(response)
 	}))
 	defer server.Close()
 
@@ -96,7 +96,7 @@ func TestTodoistClient_CreateTask_WithDueDate(t *testing.T) {
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		// Parse JSON body
 		var payload map[string]interface{}
-		json.NewDecoder(r.Body).Decode(&payload)
+		_ = json.NewDecoder(r.Body).Decode(&payload)
 
 		// Verify due_date
 		if payload["due_date"] != "2026-01-15" {
@@ -117,7 +117,7 @@ func TestTodoistClient_CreateTask_WithDueDate(t *testing.T) {
 		}
 
 		w.Header().Set("Content-Type", "application/json")
-		json.NewEncoder(w).Encode(response)
+		_ = json.NewEncoder(w).Encode(response)
 	}))
 	defer server.Close()
 
@@ -181,7 +181,7 @@ func TestTodoistClient_CompleteTask_Error(t *testing.T) {
 	// Mock server that returns error
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusNotFound)
-		w.Write([]byte(`{"error":"Task not found"}`))
+		_, _ = w.Write([]byte(`{"error":"Task not found"}`))
 	}))
 	defer server.Close()
 
@@ -218,7 +218,7 @@ func TestTodoistClient_GetProjects(t *testing.T) {
 		}
 
 		w.Header().Set("Content-Type", "application/json")
-		json.NewEncoder(w).Encode(response)
+		_ = json.NewEncoder(w).Encode(response)
 	}))
 	defer server.Close()