feat(13-03): implement TerraformSource and HelmSource

- Terraform searches registry.terraform.io v1 modules API with namespace/name/provider URLs
- Helm searches artifacthub.io for charts (kind=0) with repo/chart URL construction
- Both sources: context cancellation, nil registry, httptest-based tests

pkg/recon/sources/helm.go

@@ -0,0 +1,137 @@
+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"
+)
+
+// HelmSource searches Artifact Hub for Helm charts (kind=0) matching provider
+// keywords. Helm charts that reference LLM/AI services may contain API keys
+// in their default values.yaml files.
+//
+// Emits one Finding per chart result, tagged SourceType=recon:helm.
+type HelmSource struct {
+	// BaseURL defaults to https://artifacthub.io. 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 HelmSource satisfies recon.ReconSource.
+var _ recon.ReconSource = (*HelmSource)(nil)
+
+func (s *HelmSource) Name() string          { return "helm" }
+func (s *HelmSource) RateLimit() rate.Limit { return rate.Every(2 * time.Second) }
+func (s *HelmSource) Burst() int            { return 2 }
+func (s *HelmSource) RespectsRobots() bool  { return false }
+
+// Enabled always returns true: Artifact Hub search is unauthenticated.
+func (s *HelmSource) Enabled(_ recon.Config) bool { return true }
+
+// Sweep iterates provider keywords, searches Artifact Hub for Helm charts
+// (kind=0), and emits a Finding for each result.
+func (s *HelmSource) Sweep(ctx context.Context, _ string, out chan<- recon.Finding) error {
+	base := s.BaseURL
+	if base == "" {
+		base = "https://artifacthub.io"
+	}
+	client := s.Client
+	if client == nil {
+		client = NewClient()
+	}
+
+	queries := BuildQueries(s.Registry, "helm")
+	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
+			}
+		}
+
+		// kind=0 filters to Helm charts only.
+		endpoint := fmt.Sprintf("%s/api/v1/packages/search?ts_query_web=%s&kind=0&limit=20",
+			base, url.QueryEscape(q))
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
+		if err != nil {
+			return fmt.Errorf("helm: build req: %w", err)
+		}
+		req.Header.Set("Accept", "application/json")
+
+		resp, err := client.Do(ctx, req)
+		if err != nil {
+			continue
+		}
+
+		var parsed artifactHubSearchResponse
+		decErr := json.NewDecoder(resp.Body).Decode(&parsed)
+		_ = resp.Body.Close()
+		if decErr != nil {
+			continue
+		}
+
+		for _, pkg := range parsed.Packages {
+			if err := ctx.Err(); err != nil {
+				return err
+			}
+
+			repoName := pkg.Repository.Name
+			sourceURL := fmt.Sprintf("https://artifacthub.io/packages/helm/%s/%s",
+				repoName, pkg.NormalizedName)
+			if base != "https://artifacthub.io" {
+				sourceURL = fmt.Sprintf("%s/packages/helm/%s/%s",
+					base, repoName, pkg.NormalizedName)
+			}
+
+			f := recon.Finding{
+				ProviderName: "",
+				Source:       sourceURL,
+				SourceType:   "recon:helm",
+				Confidence:   "low",
+				DetectedAt:   time.Now(),
+			}
+			select {
+			case out <- f:
+			case <-ctx.Done():
+				return ctx.Err()
+			}
+		}
+	}
+	return nil
+}
+
+type artifactHubSearchResponse struct {
+	Packages []artifactHubPackage `json:"packages"`
+}
+
+type artifactHubPackage struct {
+	PackageID      string          `json:"package_id"`
+	Name           string          `json:"name"`
+	NormalizedName string          `json:"normalized_name"`
+	Repository     artifactHubRepo `json:"repository"`
+}
+
+type artifactHubRepo struct {
+	Name string `json:"name"`
+	Kind int    `json:"kind"`
+}