feat(tenant): inject brand description context into every generation path

Include the current brand description in template, custom, imitation,
and KOL article-generation prompts while bounding prompt growth.

- Add a shared brand-context builder that resolves the current brand,
  compacts long descriptions, and caps rendered output at 2000 runes.
- Snapshot a structured brand prompt context on queued tasks so old
  jobs stay reproducible and retries stay stable.
- Route brand-profile facts through the existing typed fact guard so
  founding dates and year counts get the same pre-persistence validation
  as RAG facts, with brand facts outranking conflicting RAG facts.
- Fix the KOL creator to attach the brand scope its worker consumes.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/internal/tenant/app/generation_task_runtime.go

@@ -332,13 +332,14 @@ func (s *PromptRuleGenerationService) ProcessQueuedTask(ctx context.Context, tas
 	}
 
 	job := promptRuleGenerationJob{
-		OperatorID:    task.OperatorID,
-		TenantID:      task.TenantID,
-		ArticleID:     task.ArticleID,
-		TaskID:        task.ID,
-		ReservationID: task.QuotaReservationID,
-		InputParams:   inputParams,
-		InitialTitle:  initialTitle,
+		OperatorID:               task.OperatorID,
+		TenantID:                 task.TenantID,
+		ArticleID:                task.ArticleID,
+		TaskID:                   task.ID,
+		ReservationID:            task.QuotaReservationID,
+		InputParams:              inputParams,
+		InitialTitle:             initialTitle,
+		KnowledgeFactConstraints: extractKnowledgeFactConstraints(inputParams),
 		WebSearch: llm.WebSearchOptions{
 			Enabled: extractBool(inputParams, "enable_web_search"),
 		},
@@ -364,9 +365,17 @@ func (s *PromptRuleGenerationService) ProcessQueuedTask(ctx context.Context, tas
 			return
 		}
 	}
+	brandID, brandPromptContext, err := ResolveGenerationBrandPromptContext(ctx, s.pool, task.TenantID, task.ArticleID, inputParams)
+	if err != nil {
+		s.failGeneration(context.Background(), job, initialTitle, "brand_context_load", err)
+		return
+	}
+	inputParams["brand_id"] = brandID
+	inputParams = attachBrandPromptContext(inputParams, brandPromptContext)
+	job.InputParams = inputParams
 
 	knowledgePrompt := strings.TrimSpace(extractString(inputParams, generationPayloadKnowledgePrompt))
-	if knowledgePrompt == "" {
+	if knowledgePrompt == "" || len(job.KnowledgeFactConstraints) == 0 {
 		if knowledgeGroupIDs := extractKnowledgeGroupIDs(inputParams["knowledge_group_ids"]); len(knowledgeGroupIDs) > 0 {
 			if s.knowledge == nil {
 				s.failGeneration(context.Background(), job, initialTitle, "knowledge_resolve", fmt.Errorf("knowledge service is not configured"))
@@ -384,9 +393,13 @@ func (s *PromptRuleGenerationService) ProcessQueuedTask(ctx context.Context, tas
 				s.failGeneration(context.Background(), job, initialTitle, "knowledge_resolve", err)
 				return
 			}
-			knowledgePrompt = s.knowledge.RenderPromptSection(knowledgeContext)
+			if knowledgePrompt == "" {
+				knowledgePrompt = s.knowledge.RenderPromptSection(knowledgeContext)
+			}
+			job.KnowledgeFactConstraints = knowledgeContext.FactConstraints
 		}
 	}
+	job.KnowledgeFactConstraints = MergeKnowledgeFactConstraints(brandPromptContext.FactConstraints, job.KnowledgeFactConstraints)
 
 	job.Prompt = buildPromptRuleGenerationPrompt(rule, inputParams, knowledgePrompt)
 	s.executeGeneration(ctx, job)