feat(keywords): rename brand-question terminology to search-keyword + add entity exclusion

- Rename UI/prompt labels: "品牌主问题" → "优化关键词", "搜索问题" → "搜索词"
- Add brand/competitor entity exclusion filter in question expansion (AI distill path)
- Refactor combination question text normalization, remove manual question-mark appending
- Update prompts to emphasize commercial-intent search queries over editorial phrasing
- Sync prompt changes across server/configs, deploy, and k3s configs
- Update i18n, frontend views (BrandQuestionCreate, TemplateWizard), and test fixtures

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

server/internal/tenant/app/question_metadata_classify.go

@@ -29,11 +29,20 @@ type ClassifiedQuestion struct {
 }
 
 func normalizeQuestionText(text string) string {
-	return strings.TrimSpace(text)
+	trimmed := strings.TrimSpace(text)
+	if trimmed == "" {
+		return ""
+	}
+	return strings.Map(func(r rune) rune {
+		if unicode.IsPunct(r) {
+			return -1
+		}
+		return r
+	}, trimmed)
 }
 
 func normalizeQuestionKey(text string) string {
-	return strings.ToLower(strings.TrimSpace(text))
+	return strings.ToLower(normalizeQuestionText(text))
 }
 
 func isValidQuestionLayer(value string) bool {