feat(theme): 暗黑模式 Phase 2 批次 2 — services/service-detail/solution-value token 化

将 services-content-v3（7 处）、service-detail-content-v4（7 处）、
solution-value（1 处）的浅色 bg-white 全部迁移到 bg-bg-primary。
浅色下值完全等价（#FFFFFF）→ 浅色视觉零差异；dark 下随 token 自动
反色为 #0A0E14，section 间 bg-bg-secondary 层次交替保留。

【变更】
- services-content-v3.tsx（7 处）：Hero + section + 卡片×3 + main wrapper
  （含卡片条件 className 中两个 bg-white 分支）
- service-detail-content-v4.tsx（7 处）：Hero + FeaturesSection + 卡片×3 +
  CasesSection + main wrapper
- solution-value.tsx（1 处）：共享 section 组件

【验证】
- type-check 0 / lint 0 errors（127 warnings 既有）
- jest 128 suites / 1623 passed
- 视觉回归 22 passed（含 /services 与 /services/software 浅色快照零 diff）
- computed-style 一次性脚本验证（已删除）：
  dark: /services 与 /services/software 的 html/body/header → #0A0E14
  section 层次 [primary, secondary, primary, secondary] 自动反色正确
  light: 零深色残留

【Phase 2 剩余批次】
- 批次 3：product-detail-content-v3 + products/standalone + detail-hero 共享组件
- 批次 4：admin 全量（user决策：参与暗黑）

src/app/(marketing)/services/service-detail-content-v4.tsx

@@ -14,7 +14,7 @@ function DetailHero({ service }: { service: Service }) {
   const firstBenefit = service.benefits?.[0] || '效率提升 40%';
 
   return (
-    <section className="relative min-h-[85vh] flex items-center overflow-hidden bg-white">
+    <section className="relative min-h-[85vh] flex items-center overflow-hidden bg-bg-primary">
       <div className="max-w-container mx-auto px-4 sm:px-6 lg:px-10 relative z-10 w-full py-28 sm:py-36 md:py-44 lg:py-56">
         <div className="max-w-4xl">
           <motion.h1
@@ -147,7 +147,7 @@ function OverviewSection({ service }: { service: Service }) {
 
 function FeaturesSection({ service }: { service: Service }) {
   return (
-    <section className="relative py-20 sm:py-28 md:py-36 lg:py-44 overflow-hidden bg-white">
+    <section className="relative py-20 sm:py-28 md:py-36 lg:py-44 overflow-hidden bg-bg-primary">
       <div className="max-w-container mx-auto px-4 sm:px-6 lg:px-10">
         <motion.div
           initial={{ opacity: 0, y: 30 }}
@@ -176,7 +176,7 @@ function FeaturesSection({ service }: { service: Service }) {
                 whileInView={{ opacity: 1, y: 0 }}
                 viewport={{ once: true, margin: '-60px' }}
                 transition={{ duration: 0.6, delay: index * 0.06, ease: EASE_OUT }}
-                className="group relative p-8 sm:p-10 transition-all duration-500 hover:bg-bg-secondary hover:shadow-lg hover:-translate-y-1 bg-white"
+                className="group relative p-8 sm:p-10 transition-all duration-500 hover:bg-bg-secondary hover:shadow-lg hover:-translate-y-1 bg-bg-primary"
               >
                 <div className="relative z-10">
                   <Icon className="w-8 h-8 mb-6 text-brand" />
@@ -230,7 +230,7 @@ function ProcessSection({ service }: { service: Service }) {
                 whileInView={{ opacity: 1, y: 0 }}
                 viewport={{ once: true, margin: '-60px' }}
                 transition={{ duration: 0.6, delay: index * 0.08, ease: EASE_OUT }}
-                className="relative group p-6 sm:p-8 bg-white hover:bg-bg-secondary hover:shadow-lg hover:-translate-y-1 transition-all duration-500"
+                className="relative group p-6 sm:p-8 bg-bg-primary hover:bg-bg-secondary hover:shadow-lg hover:-translate-y-1 transition-all duration-500"
               >
                 <div
                   className="w-2 h-2 rounded-full mb-6"
@@ -255,7 +255,7 @@ function CaseStudiesSection({ caseStudies = [] }: { caseStudies?: CaseStudy[] })
   if (caseStudies.length === 0) return null;
 
   return (
-    <section id="cases" className="relative py-20 sm:py-28 md:py-36 lg:py-44 overflow-hidden bg-white">
+    <section id="cases" className="relative py-20 sm:py-28 md:py-36 lg:py-44 overflow-hidden bg-bg-primary">
       <div className="max-w-container mx-auto px-4 sm:px-6 lg:px-10">
         <motion.div
           initial={{ opacity: 0, y: 30 }}
@@ -278,7 +278,7 @@ function CaseStudiesSection({ caseStudies = [] }: { caseStudies?: CaseStudy[] })
               whileInView={{ opacity: 1, y: 0 }}
               viewport={{ once: true, margin: '-60px' }}
               transition={{ duration: 0.6, delay: i * 0.08, ease: EASE_OUT }}
-              className="group relative block p-8 sm:p-10 transition-all duration-500 hover:bg-bg-secondary hover:shadow-lg hover:-translate-y-1 bg-white border border-transparent hover:border-border-primary"
+              className="group relative block p-8 sm:p-10 transition-all duration-500 hover:bg-bg-secondary hover:shadow-lg hover:-translate-y-1 bg-bg-primary border border-transparent hover:border-border-primary"
             >
 
               <div className="relative z-10">
@@ -348,7 +348,7 @@ function CTASection() {
 
 export default function ServiceDetailContentV4({ service }: { service: Service }) {
   return (
-    <main className="min-h-screen bg-white text-ink">
+    <main className="min-h-screen bg-bg-primary text-ink">
       <DetailHero service={service} />
       <OverviewSection service={service} />
       <FeaturesSection service={service} />