feat: unify NofxOS data provider and fix language consistency

- Add unified NofxOS API key configuration in IndicatorEditor
- Add language field to StrategyConfig for consistent prompt generation
- Auto-update prompt sections when interface language changes
- Remove scattered URL inputs from CoinSourceEditor and IndicatorEditor
- Create nofxos provider package with formatted data output
- Update kernel engine to use config-based language setting

provider/nofxos/client.go

@@ -0,0 +1,146 @@
+// Package nofxos provides data access to the NofxOS API (https://nofxos.ai)
+// for quantitative trading data including AI500 scores, OI rankings,
+// fund flow (NetFlow), price rankings, and coin details.
+package nofxos
+
+import (
+	"io/ioutil"
+	"net/http"
+	"nofx/security"
+	"strings"
+	"sync"
+	"time"
+)
+
+// Default configuration
+const (
+	DefaultBaseURL = "https://nofxos.ai"
+	DefaultTimeout = 30 * time.Second
+	DefaultAuthKey = "cm_568c67eae410d912c54c"
+)
+
+// Client is the NofxOS API client
+type Client struct {
+	BaseURL string
+	AuthKey string
+	Timeout time.Duration
+	mu      sync.RWMutex
+}
+
+var (
+	defaultClient *Client
+	clientOnce    sync.Once
+)
+
+// DefaultClient returns the singleton default client
+func DefaultClient() *Client {
+	clientOnce.Do(func() {
+		defaultClient = &Client{
+			BaseURL: DefaultBaseURL,
+			AuthKey: DefaultAuthKey,
+			Timeout: DefaultTimeout,
+		}
+	})
+	return defaultClient
+}
+
+// NewClient creates a new NofxOS API client
+func NewClient(baseURL, authKey string) *Client {
+	if baseURL == "" {
+		baseURL = DefaultBaseURL
+	}
+	if authKey == "" {
+		authKey = DefaultAuthKey
+	}
+	return &Client{
+		BaseURL: baseURL,
+		AuthKey: authKey,
+		Timeout: DefaultTimeout,
+	}
+}
+
+// SetConfig updates client configuration
+func (c *Client) SetConfig(baseURL, authKey string) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if baseURL != "" {
+		c.BaseURL = baseURL
+	}
+	if authKey != "" {
+		c.AuthKey = authKey
+	}
+}
+
+// GetBaseURL returns the current base URL
+func (c *Client) GetBaseURL() string {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	return c.BaseURL
+}
+
+// GetAuthKey returns the current auth key
+func (c *Client) GetAuthKey() string {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	return c.AuthKey
+}
+
+// doRequest performs an HTTP GET request with authentication
+func (c *Client) doRequest(endpoint string) ([]byte, error) {
+	c.mu.RLock()
+	baseURL := c.BaseURL
+	authKey := c.AuthKey
+	timeout := c.Timeout
+	c.mu.RUnlock()
+
+	url := baseURL + endpoint
+	if !strings.Contains(url, "auth=") {
+		if strings.Contains(url, "?") {
+			url += "&auth=" + authKey
+		} else {
+			url += "?auth=" + authKey
+		}
+	}
+
+	resp, err := security.SafeGet(url, timeout)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return body, &APIError{
+			StatusCode: resp.StatusCode,
+			Message:    string(body),
+		}
+	}
+
+	return body, nil
+}
+
+// APIError represents an API error response
+type APIError struct {
+	StatusCode int
+	Message    string
+}
+
+func (e *APIError) Error() string {
+	return e.Message
+}
+
+// ExtractAuthKey extracts auth key from a URL string
+func ExtractAuthKey(url string) string {
+	if idx := strings.Index(url, "auth="); idx != -1 {
+		authKey := url[idx+5:]
+		if ampIdx := strings.Index(authKey, "&"); ampIdx != -1 {
+			authKey = authKey[:ampIdx]
+		}
+		return authKey
+	}
+	return ""
+}