feat(11-01): add GoogleDorkSource and BingDorkSource with formatQuery updates

- GoogleDorkSource uses Google Custom Search JSON API (APIKey+CX required)
- BingDorkSource uses Bing Web Search API v7 (Ocp-Apim-Subscription-Key header)
- formatQuery now handles google/bing/duckduckgo/yandex/brave dork syntax
- Both sources follow established pattern: retry via Client, rate limit via LimiterRegistry

pkg/recon/sources/bing.go

@@ -0,0 +1,155 @@
+package sources
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	"golang.org/x/time/rate"
+
+	"github.com/salvacybersec/keyhunter/pkg/providers"
+	"github.com/salvacybersec/keyhunter/pkg/recon"
+)
+
+// BingDorkSource implements recon.ReconSource against the Bing Web Search
+// API v7. It iterates provider keyword queries and emits a Finding per result.
+//
+// A missing API key disables the source without error.
+type BingDorkSource struct {
+	APIKey   string
+	BaseURL  string
+	Registry *providers.Registry
+	Limiters *recon.LimiterRegistry
+	client   *Client
+}
+
+// Compile-time assertion.
+var _ recon.ReconSource = (*BingDorkSource)(nil)
+
+// NewBingDorkSource constructs a BingDorkSource with the shared retry client.
+func NewBingDorkSource(apiKey string, reg *providers.Registry, lim *recon.LimiterRegistry) *BingDorkSource {
+	return &BingDorkSource{
+		APIKey:   apiKey,
+		BaseURL:  "https://api.bing.microsoft.com",
+		Registry: reg,
+		Limiters: lim,
+		client:   NewClient(),
+	}
+}
+
+func (s *BingDorkSource) Name() string          { return "bing" }
+func (s *BingDorkSource) RateLimit() rate.Limit { return rate.Every(500 * time.Millisecond) }
+func (s *BingDorkSource) Burst() int            { return 2 }
+func (s *BingDorkSource) RespectsRobots() bool  { return false }
+
+// Enabled returns true only when APIKey is configured.
+func (s *BingDorkSource) Enabled(_ recon.Config) bool { return s.APIKey != "" }
+
+// Sweep issues one Bing Web Search request per provider keyword and emits a
+// Finding for every webPages.value result.
+func (s *BingDorkSource) Sweep(ctx context.Context, _ string, out chan<- recon.Finding) error {
+	if s.APIKey == "" {
+		return nil
+	}
+	base := s.BaseURL
+	if base == "" {
+		base = "https://api.bing.microsoft.com"
+	}
+
+	queries := BuildQueries(s.Registry, "bing")
+	kwIndex := bingKeywordIndex(s.Registry)
+
+	for _, q := range queries {
+		if err := ctx.Err(); err != nil {
+			return err
+		}
+		if s.Limiters != nil {
+			if err := s.Limiters.Wait(ctx, s.Name(), s.RateLimit(), s.Burst(), false); err != nil {
+				return err
+			}
+		}
+
+		endpoint := fmt.Sprintf("%s/v7.0/search?q=%s&count=50", base, url.QueryEscape(q))
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
+		if err != nil {
+			return fmt.Errorf("bing: build request: %w", err)
+		}
+		req.Header.Set("Ocp-Apim-Subscription-Key", s.APIKey)
+		req.Header.Set("Accept", "application/json")
+		req.Header.Set("User-Agent", "keyhunter-recon")
+
+		resp, err := s.client.Do(ctx, req)
+		if err != nil {
+			if errors.Is(err, ErrUnauthorized) {
+				return err
+			}
+			if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
+				return err
+			}
+			continue
+		}
+
+		var parsed bingSearchResponse
+		decErr := json.NewDecoder(resp.Body).Decode(&parsed)
+		_ = resp.Body.Close()
+		if decErr != nil {
+			continue
+		}
+
+		provName := kwIndex[strings.ToLower(extractGoogleKeyword(q))]
+		for _, it := range parsed.WebPages.Value {
+			f := recon.Finding{
+				ProviderName: provName,
+				Confidence:   "low",
+				Source:       it.URL,
+				SourceType:   "recon:bing",
+				DetectedAt:   time.Now(),
+			}
+			select {
+			case out <- f:
+			case <-ctx.Done():
+				return ctx.Err()
+			}
+		}
+	}
+	return nil
+}
+
+type bingSearchResponse struct {
+	WebPages bingWebPages `json:"webPages"`
+}
+
+type bingWebPages struct {
+	Value []bingWebResult `json:"value"`
+}
+
+type bingWebResult struct {
+	Name    string `json:"name"`
+	URL     string `json:"url"`
+	Snippet string `json:"snippet"`
+}
+
+// bingKeywordIndex maps lowercased keywords to provider names.
+func bingKeywordIndex(reg *providers.Registry) map[string]string {
+	m := make(map[string]string)
+	if reg == nil {
+		return m
+	}
+	for _, p := range reg.List() {
+		for _, k := range p.Keywords {
+			kl := strings.ToLower(strings.TrimSpace(k))
+			if kl == "" {
+				continue
+			}
+			if _, exists := m[kl]; !exists {
+				m[kl] = p.Name
+			}
+		}
+	}
+	return m
+}