refactor: remove SearXNG references and rename binary to kafka

- Rename cmd/searxng-go to cmd/kafka
- Remove all SearXNG references from source comments while keeping
  "SearXNG-compatible API" in user-facing docs
- Update binary paths in README, CLAUDE.md, and Dockerfile
- Update log message to "kafka starting"

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/engines/braveapi.go

@@ -14,7 +14,7 @@ import (
 	"github.com/metamorphosis-dev/kafka/internal/contracts"
 )
 
-// BraveEngine implements the SearXNG `braveapi` engine (Brave Web Search API).
+// BraveEngine implements the `braveapi` engine (Brave Web Search API).
 //
 // Config / gating:
 // - BRAVE_API_KEY: required to call Brave
@@ -35,8 +35,8 @@ func (e *BraveEngine) Search(ctx context.Context, req contracts.SearchRequest) (
 		return contracts.SearchResponse{}, errors.New("brave engine not initialized")
 	}
 
-	// Gate / config checks should not be treated as fatal errors; SearXNG
-	// treats misconfigured engines as unresponsive.
+	// Gate / config checks should not be treated as fatal errors; the reference
+	// implementation treats misconfigured engines as unresponsive.
 	if strings.TrimSpace(e.apiKey) == "" {
 		return contracts.SearchResponse{
 			Query:               req.Query,
@@ -93,7 +93,7 @@ func (e *BraveEngine) Search(ctx context.Context, req contracts.SearchRequest) (
 		}
 	}
 
-	// SearXNG's python checks `if params["safesearch"]:` which treats any
+	// The reference implementation checks `if params["safesearch"]:` which treats any
 	// non-zero (moderate/strict) as strict.
 	if req.Safesearch > 0 {
 		args.Set("safesearch", "strict")

internal/engines/engine.go

@@ -6,7 +6,7 @@ import (
 	"github.com/metamorphosis-dev/kafka/internal/contracts"
 )
 
-// Engine is a Go-native implementation of a SearXNG engine.
+// Engine is a Go-native implementation of a search engine.
 //
 // Implementations should return a SearchResponse containing only the results
 // for that engine subset; the caller will merge multiple engine responses.

internal/engines/planner.go

@@ -48,7 +48,7 @@ func NewPlanner(portedEngines []string) *Planner {
 
 // Plan returns:
 // - localEngines: engines that are configured as ported for this service
-// - upstreamEngines: engines that should be executed by upstream SearXNG
+// - upstreamEngines: engines that should be executed by the upstream instance
 // - requestedEngines: the (possibly inferred) requested engines list
 //
 // If the request provides an explicit `engines` parameter, we use it.
@@ -80,7 +80,7 @@ func (p *Planner) Plan(req contracts.SearchRequest) (localEngines, upstreamEngin
 
 func inferFromCategories(categories []string) []string {
 	// Minimal mapping for the initial porting subset.
-	// This mirrors the idea of selecting from SearXNG categories without
+	// This mirrors the idea of selecting from engine categories without
 	// embedding the whole engine registry.
 	set := map[string]bool{}
 	for _, c := range categories {

internal/engines/qwant.go

@@ -14,11 +14,11 @@ import (
 	"github.com/PuerkitoBio/goquery"
 )
 
-// QwantEngine implements a SearXNG-like `qwant` (web) adapter using
+// QwantEngine implements a `qwant` (web) adapter using
 // Qwant v3 endpoint: https://api.qwant.com/v3/search/web.
 //
-// Qwant's API is not fully documented; this mirrors SearXNG's parsing logic
-// for the `web` category from `.agent/searxng/searx/engines/qwant.py`.
+// Qwant's API is not fully documented; this implements parsing logic
+// for the `web` category.
 type QwantEngine struct {
 	client        *http.Client
 	category      string // "web" (JSON API) or "web-lite" (HTML fallback)
@@ -37,7 +37,7 @@ func (e *QwantEngine) Search(ctx context.Context, req contracts.SearchRequest) (
 		return contracts.SearchResponse{Query: req.Query}, nil
 	}
 
-	// For API parity we use SearXNG web defaults: count=10, offset=(pageno-1)*count.
+	// For API parity we use web defaults: count=10, offset=(pageno-1)*count.
 	// The engine's config field exists so we can expand to news/images/videos later.
 	count := e.resultsPerPage
 	if count <= 0 {
@@ -262,7 +262,7 @@ func (e *QwantEngine) searchWebLite(ctx context.Context, req contracts.SearchReq
 			return
 		}
 
-		// In SearXNG: "./span[contains(@class, 'url partner')]"
+		// Selector: "./span[contains(@class, 'url partner')]"
 		urlText := strings.TrimSpace(item.Find("span.url.partner").First().Text())
 		if urlText == "" {
 			// fallback: any span with class containing both 'url' and 'partner'