feat(ui): dark theme redesign, fix image search and defaults

- Inline CSS in base.html (Inter, dark mode, sticky search, tabs, results)
- Remove HTMX/JS from templates; pagination via GET links
- Atmospheric side gradients + grid; wider column on large viewports
- Parse ?category= for HTML tabs (fixes Images category routing)
- Include bing_images, ddg_images, qwant_images in local_ported defaults
- Default listen port 5355; update Docker, compose, flake, README
- Favicon img uses /favicon/ proxy; preferences without inline JS

Made-with: Cursor

internal/search/request_params.go

@@ -161,6 +161,10 @@ func ParseSearchRequest(r *http.Request) (SearchRequest, error) {
 			delete(catSet, category)
 		}
 	}
+	// HTML UI uses a single ?category=images (etc.) query param; honor it here.
+	if single := strings.TrimSpace(r.FormValue("category")); single != "" {
+		catSet[single] = true
+	}
 	categories := make([]string, 0, len(catSet))
 	for c := range catSet {
 		categories = append(categories, c)
@@ -196,16 +200,16 @@ func ParseSearchRequest(r *http.Request) (SearchRequest, error) {
 
 	return SearchRequest{
 		Format:       OutputFormat(format),
-		Query:       q,
-		Pageno:      pageno,
-		Safesearch:  safesearch,
-		TimeRange:   timeRange,
+		Query:        q,
+		Pageno:       pageno,
+		Safesearch:   safesearch,
+		TimeRange:    timeRange,
 		TimeoutLimit: timeoutLimit,
-		Language:    language,
-		Engines:     engines,
-		Categories:  categories,
-		EngineData:  engineData,
-		AccessToken: accessToken,
+		Language:     language,
+		Engines:      engines,
+		Categories:   categories,
+		EngineData:   engineData,
+		AccessToken:  accessToken,
 	}, nil
 }
 
@@ -250,4 +254,3 @@ func parseAccessToken(r *http.Request) string {
 
 	return ""
 }
-