feat(13-03): implement DockerHubSource and KubernetesSource

- DockerHub searches hub.docker.com v2 search API for repos matching provider keywords
- Kubernetes searches Artifact Hub for operators/manifests with kind-aware URL paths
- Both sources: context cancellation, nil registry, httptest-based tests

pkg/recon/sources/dockerhub.go

@@ -0,0 +1,125 @@
+package sources
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"time"
+
+	"golang.org/x/time/rate"
+
+	"github.com/salvacybersec/keyhunter/pkg/providers"
+	"github.com/salvacybersec/keyhunter/pkg/recon"
+)
+
+// DockerHubSource searches Docker Hub for public images matching provider
+// keywords. Unauthenticated search is rate-limited but freely accessible.
+//
+// Emits one Finding per repository result, tagged SourceType=recon:dockerhub.
+type DockerHubSource struct {
+	// BaseURL defaults to https://hub.docker.com. Tests override with httptest URL.
+	BaseURL string
+	// Registry drives the keyword query list via BuildQueries.
+	Registry *providers.Registry
+	// Limiters is the shared recon.LimiterRegistry.
+	Limiters *recon.LimiterRegistry
+	// Client is the shared retry HTTP wrapper. If nil, a default is used.
+	Client *Client
+}
+
+// Compile-time assertion that DockerHubSource satisfies recon.ReconSource.
+var _ recon.ReconSource = (*DockerHubSource)(nil)
+
+func (s *DockerHubSource) Name() string          { return "dockerhub" }
+func (s *DockerHubSource) RateLimit() rate.Limit { return rate.Every(2 * time.Second) }
+func (s *DockerHubSource) Burst() int            { return 2 }
+func (s *DockerHubSource) RespectsRobots() bool  { return false }
+
+// Enabled always returns true: Docker Hub search is unauthenticated.
+func (s *DockerHubSource) Enabled(_ recon.Config) bool { return true }
+
+// Sweep iterates provider keywords, searches Docker Hub for matching
+// repositories, and emits a Finding for each result.
+func (s *DockerHubSource) Sweep(ctx context.Context, _ string, out chan<- recon.Finding) error {
+	base := s.BaseURL
+	if base == "" {
+		base = "https://hub.docker.com"
+	}
+	client := s.Client
+	if client == nil {
+		client = NewClient()
+	}
+
+	queries := BuildQueries(s.Registry, "dockerhub")
+	if len(queries) == 0 {
+		return nil
+	}
+
+	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/v2/search/repositories/?query=%s&page_size=20",
+			base, url.QueryEscape(q))
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
+		if err != nil {
+			return fmt.Errorf("dockerhub: build req: %w", err)
+		}
+		req.Header.Set("Accept", "application/json")
+
+		resp, err := client.Do(ctx, req)
+		if err != nil {
+			// Non-fatal: skip this keyword on transient errors.
+			continue
+		}
+
+		var parsed dockerHubSearchResponse
+		decErr := json.NewDecoder(resp.Body).Decode(&parsed)
+		_ = resp.Body.Close()
+		if decErr != nil {
+			continue
+		}
+
+		for _, repo := range parsed.Results {
+			if err := ctx.Err(); err != nil {
+				return err
+			}
+			sourceURL := fmt.Sprintf("https://hub.docker.com/r/%s", repo.RepoName)
+			if base != "https://hub.docker.com" {
+				sourceURL = fmt.Sprintf("%s/r/%s", base, repo.RepoName)
+			}
+			f := recon.Finding{
+				ProviderName: "",
+				Source:       sourceURL,
+				SourceType:   "recon:dockerhub",
+				Confidence:   "low",
+				DetectedAt:   time.Now(),
+			}
+			select {
+			case out <- f:
+			case <-ctx.Done():
+				return ctx.Err()
+			}
+		}
+	}
+	return nil
+}
+
+type dockerHubSearchResponse struct {
+	Results []dockerHubRepo `json:"results"`
+}
+
+type dockerHubRepo struct {
+	RepoName    string `json:"repo_name"`
+	Description string `json:"description"`
+	IsOfficial  bool   `json:"is_official"`
+}