feat(14-03): implement SourceMapSource, WebpackSource, EnvLeakSource with tests

- SourceMapSource probes .map files for original source containing API keys
- WebpackSource scans JS bundles for inlined NEXT_PUBLIC_/REACT_APP_/VITE_ env vars
- EnvLeakSource probes common .env paths for exposed environment files
- All three implement ReconSource, credentialless, with httptest-based tests

pkg/recon/sources/envleak.go

@@ -0,0 +1,111 @@
+package sources
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"regexp"
+	"time"
+
+	"golang.org/x/time/rate"
+
+	"github.com/salvacybersec/keyhunter/pkg/providers"
+	"github.com/salvacybersec/keyhunter/pkg/recon"
+)
+
+// EnvLeakSource probes for publicly accessible .env files on web servers.
+// Many web frameworks (Laravel, Rails, Node/Express, Django) use .env files
+// for configuration. Misconfigured servers frequently serve these files
+// directly, exposing API keys and database credentials.
+type EnvLeakSource struct {
+	BaseURL  string
+	Registry *providers.Registry
+	Limiters *recon.LimiterRegistry
+	Client   *Client
+}
+
+var _ recon.ReconSource = (*EnvLeakSource)(nil)
+
+func (s *EnvLeakSource) Name() string              { return "dotenv" }
+func (s *EnvLeakSource) RateLimit() rate.Limit      { return rate.Every(2 * time.Second) }
+func (s *EnvLeakSource) Burst() int                 { return 2 }
+func (s *EnvLeakSource) RespectsRobots() bool       { return true }
+func (s *EnvLeakSource) Enabled(_ recon.Config) bool { return true }
+
+// envKeyValuePattern matches KEY=VALUE lines typical of .env files.
+var envKeyValuePattern = regexp.MustCompile(`(?im)^[A-Z_]*(API[_]?KEY|SECRET|TOKEN|PASSWORD|CREDENTIALS?)[A-Z_]*\s*=\s*\S+`)
+
+// envFilePaths are common locations for exposed .env files.
+var envFilePaths = []string{
+	"/.env",
+	"/.env.local",
+	"/.env.production",
+	"/.env.development",
+	"/.env.backup",
+	"/.env.example",
+	"/app/.env",
+	"/api/.env",
+}
+
+func (s *EnvLeakSource) Sweep(ctx context.Context, _ string, out chan<- recon.Finding) error {
+	base := s.BaseURL
+	if base == "" {
+		return nil
+	}
+	client := s.Client
+	if client == nil {
+		client = NewClient()
+	}
+
+	queries := BuildQueries(s.Registry, "dotenv")
+	if len(queries) == 0 {
+		return nil
+	}
+
+	for _, q := range queries {
+		if err := ctx.Err(); err != nil {
+			return err
+		}
+
+		for _, path := range envFilePaths {
+			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
+				}
+			}
+
+			probeURL := fmt.Sprintf("%s%s", base, path)
+			req, err := http.NewRequestWithContext(ctx, http.MethodGet, probeURL, nil)
+			if err != nil {
+				continue
+			}
+
+			resp, err := client.Do(ctx, req)
+			if err != nil {
+				continue
+			}
+
+			body, err := io.ReadAll(io.LimitReader(resp.Body, 64*1024)) // 64KB max
+			_ = resp.Body.Close()
+			if err != nil {
+				continue
+			}
+
+			if envKeyValuePattern.Match(body) {
+				out <- recon.Finding{
+					ProviderName: q,
+					Source:       probeURL,
+					SourceType:   "recon:dotenv",
+					Confidence:   "high",
+					DetectedAt:   time.Now(),
+				}
+			}
+		}
+	}
+	return nil
+}