feat(questions): make brand questions the primary monitoring & template axis

- add /questions/combination-fill endpoint with AI-driven, IP-region-aware matrix fill
- extract ip2region resolver from ops/app into shared/ipregion for cross-service use
- thread question_id filter through dashboard composite, citation summary, and collect-now
- switch template wizard from keyword inputs to brand-question selection (primary + supplemental)
- pass brand_question and supplemental_questions through assist/title/outline prompts
- add AiWaitingModal + 45s client timeout and request_timeout error mapping for long AI flows

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/internal/shared/config/reload.go

@@ -65,6 +65,9 @@ func Diff(previous, current *Config) []FieldChange {
 	if !reflect.DeepEqual(previous.BrandLibrary, current.BrandLibrary) {
 		addChange("brand_library", true)
 	}
+	if previous.IPRegion != current.IPRegion {
+		addChange("ip_region", false)
+	}
 	if previous.Qdrant != current.Qdrant {
 		addChange("qdrant", true)
 	}