feat(10-01): add provider-driven query generator and RegisterAll skeleton

- BuildQueries(reg, source) dedups keywords and formats per-source syntax
- github/gist use 'keyword' in:file; others use bare keyword
- SourcesConfig placeholder struct for Wave 2 plans to depend on
- RegisterAll no-op stub (Plan 10-09 will fill)

pkg/recon/sources/queries.go

@@ -0,0 +1,55 @@
+package sources
+
+import (
+	"fmt"
+	"sort"
+
+	"github.com/salvacybersec/keyhunter/pkg/providers"
+)
+
+// BuildQueries produces the search-string list a source should iterate for the
+// given provider registry. Each keyword is formatted per source-specific syntax
+// (e.g. GitHub's `"kw" in:file` qualifier). Keywords are deduped across
+// providers and returned sorted for deterministic test output.
+//
+// A nil registry returns nil. An unknown source name falls back to the bare
+// keyword form so new sources work safely until they register custom syntax.
+func BuildQueries(reg *providers.Registry, source string) []string {
+	if reg == nil {
+		return nil
+	}
+
+	seen := make(map[string]struct{})
+	for _, p := range reg.List() {
+		for _, k := range p.Keywords {
+			if k == "" {
+				continue
+			}
+			seen[k] = struct{}{}
+		}
+	}
+
+	keywords := make([]string, 0, len(seen))
+	for k := range seen {
+		keywords = append(keywords, k)
+	}
+	sort.Strings(keywords)
+
+	out := make([]string, 0, len(keywords))
+	for _, k := range keywords {
+		out = append(out, formatQuery(source, k))
+	}
+	return out
+}
+
+// formatQuery applies source-specific search syntax to a raw keyword.
+func formatQuery(source, keyword string) string {
+	switch source {
+	case "github", "gist":
+		return fmt.Sprintf("%q in:file", keyword)
+	default:
+		// GitLab, Bitbucket, Codeberg, HuggingFace, Kaggle, Replit,
+		// CodeSandbox, sandboxes, and unknown sources use bare keywords.
+		return keyword
+	}
+}