feat(15-01): add Discord, Slack, DevTo recon sources and wire all six

- DiscordSource uses dorking approach against configurable search endpoint
- SlackSource uses dorking against slack-archive indexers
- DevToSource searches dev.to API articles list + detail for body_markdown
- RegisterAll extended to include all 6 Phase 15 forum sources
- All credentialless, use ciLogKeyPattern for key detection

pkg/recon/sources/slack.go

@@ -0,0 +1,110 @@
+package sources
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"time"
+
+	"golang.org/x/time/rate"
+
+	"github.com/salvacybersec/keyhunter/pkg/providers"
+	"github.com/salvacybersec/keyhunter/pkg/recon"
+)
+
+// SlackSource discovers publicly indexed Slack messages that may contain
+// leaked API keys. Slack workspaces occasionally have public archives, and
+// search engines index shared Slack content. This source uses a dorking
+// approach against a configurable search endpoint.
+type SlackSource struct {
+	BaseURL  string
+	Registry *providers.Registry
+	Limiters *recon.LimiterRegistry
+	Client   *Client
+}
+
+var _ recon.ReconSource = (*SlackSource)(nil)
+
+func (s *SlackSource) Name() string               { return "slack" }
+func (s *SlackSource) RateLimit() rate.Limit       { return rate.Every(3 * time.Second) }
+func (s *SlackSource) Burst() int                  { return 2 }
+func (s *SlackSource) RespectsRobots() bool        { return false }
+func (s *SlackSource) Enabled(_ recon.Config) bool { return true }
+
+// slackSearchResponse represents the search endpoint response for Slack dorking.
+type slackSearchResponse struct {
+	Results []slackSearchResult `json:"results"`
+}
+
+type slackSearchResult struct {
+	URL     string `json:"url"`
+	Content string `json:"content"`
+}
+
+func (s *SlackSource) Sweep(ctx context.Context, _ string, out chan<- recon.Finding) error {
+	base := s.BaseURL
+	if base == "" {
+		base = "https://search.slackarchive.dev"
+	}
+	client := s.Client
+	if client == nil {
+		client = NewClient()
+	}
+
+	queries := BuildQueries(s.Registry, "slack")
+	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/search?q=%s&format=json",
+			base, url.QueryEscape("site:slack-archive.org OR site:slack-files.com "+q))
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, searchURL, nil)
+		if err != nil {
+			continue
+		}
+		req.Header.Set("Accept", "application/json")
+
+		resp, err := client.Do(ctx, req)
+		if err != nil {
+			continue
+		}
+
+		body, err := io.ReadAll(io.LimitReader(resp.Body, 256*1024))
+		_ = resp.Body.Close()
+		if err != nil {
+			continue
+		}
+
+		var result slackSearchResponse
+		if err := json.Unmarshal(body, &result); err != nil {
+			continue
+		}
+
+		for _, item := range result.Results {
+			if ciLogKeyPattern.MatchString(item.Content) {
+				out <- recon.Finding{
+					ProviderName: q,
+					Source:       item.URL,
+					SourceType:   "recon:slack",
+					Confidence:   "low",
+					DetectedAt:   time.Now(),
+				}
+			}
+		}
+	}
+	return nil
+}