feat(13-01): implement NpmSource and PyPISource with httptest tests

- NpmSource searches npm registry JSON API for provider keywords
- PyPISource scrapes pypi.org search HTML for project links
- Both credentialless, rate-limited at 1 req/2s, burst 2
- httptest-based tests verify Sweep, ctx cancellation, Name/Rate/Burst

pkg/recon/sources/npm.go

@@ -0,0 +1,114 @@
+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"
+)
+
+// NpmSource searches the npm registry for packages matching provider keywords.
+// No credentials required. Emits findings tagged SourceType=recon:npm.
+type NpmSource struct {
+	BaseURL  string
+	Registry *providers.Registry
+	Limiters *recon.LimiterRegistry
+	Client   *Client
+}
+
+var _ recon.ReconSource = (*NpmSource)(nil)
+
+func (s *NpmSource) Name() string            { return "npm" }
+func (s *NpmSource) RateLimit() rate.Limit    { return rate.Every(2 * time.Second) }
+func (s *NpmSource) Burst() int               { return 2 }
+func (s *NpmSource) RespectsRobots() bool     { return false }
+func (s *NpmSource) Enabled(_ recon.Config) bool { return true }
+
+// npm search JSON response structs.
+type npmSearchResponse struct {
+	Objects []npmObject `json:"objects"`
+}
+
+type npmObject struct {
+	Package npmPackage `json:"package"`
+}
+
+type npmPackage struct {
+	Name  string   `json:"name"`
+	Links npmLinks `json:"links"`
+}
+
+type npmLinks struct {
+	Npm string `json:"npm"`
+}
+
+func (s *NpmSource) Sweep(ctx context.Context, _ string, out chan<- recon.Finding) error {
+	base := s.BaseURL
+	if base == "" {
+		base = "https://registry.npmjs.org"
+	}
+	client := s.Client
+	if client == nil {
+		client = NewClient()
+	}
+
+	queries := BuildQueries(s.Registry, "npm")
+	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
+			}
+		}
+
+		searchURL := fmt.Sprintf("%s/-/v1/search?text=%s&size=20", base, url.QueryEscape(q))
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, searchURL, nil)
+		if err != nil {
+			return fmt.Errorf("npm: build req: %w", err)
+		}
+
+		resp, err := client.Do(ctx, req)
+		if err != nil {
+			return fmt.Errorf("npm: fetch: %w", err)
+		}
+
+		var result npmSearchResponse
+		if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
+			_ = resp.Body.Close()
+			return fmt.Errorf("npm: decode json: %w", err)
+		}
+		_ = resp.Body.Close()
+
+		for _, obj := range result.Objects {
+			if err := ctx.Err(); err != nil {
+				return err
+			}
+			source := obj.Package.Links.Npm
+			if source == "" {
+				source = fmt.Sprintf("https://www.npmjs.com/package/%s", obj.Package.Name)
+			}
+			out <- recon.Finding{
+				ProviderName: "",
+				Source:       source,
+				SourceType:   "recon:npm",
+				Confidence:   "low",
+				DetectedAt:   time.Now(),
+			}
+		}
+	}
+	return nil
+}