feat: 更新产品类型和内容，优化产品展示功能

- 重构产品类型定义，新增desc、models、content字段
- 更新所有语言的产品内容，包括详细规格和化学/机械性能
- 修改产品展示组件，支持MDX内容渲染和模型列表展示
- 调整产品详情页布局，优化信息展示方式
- 更新i18n翻译文件，同步产品名称变更
- 修改默认主题配置为light模式
- 修复公司简介中的格式问题

content/product/en/5.mdx

@@ -0,0 +1,31 @@
+---
+title: Cold-Rolled Low Carbon Steel Sheet
+desc: Has high strength and good welding performance, excellent surface quality and shape, suitable for hardware, pipes and building structural parts that have certain requirements for strength and processing performance.
+models: 
+  - GB/T 11253-2007: Q235
+  - 2011 JX(19): LQ215
+  - 2011 JX(21): THD
+spec: 
+  - 'Thickness: 0.6~2.0mm'
+  - 'Width: 1000~1540mm'
+slug: '5'
+---
+
+## Chemical Composition
+| Grade | C | Mn | Si | P | S |
+| :--- | :--- | :--- | :--- | :--- | :--- |
+| Q235 | ≤0.22 | ≤1.40 | ≤0.35 | ≤0.035 | ≤0.035 |
+| DX51D | ≤0.22 | ≤1.20 | ≤0.35 | ≤0.035 | ≤0.035 |
+| S350GD | ≤0.22 | ≤1.20 | ≤0.35 | ≤0.035 | ≤0.035 |
+
+## Mechanical Properties
+| Grades | Yield strength/Re/MPa | Tensile strength/Rm/MPa | Elongation/A80/% | Hardness/HRB | 180° bending test (bend diameter d) |
+| :--- | :--- | :--- | :--- | :--- | :--- |
+| Q235 | ≥235 | 370-500 | ≥22 | - | d=1a |
+| LQ215 | ≥215 | 335-450 | ≥24 | - | d=0.5a |
+| THD | - | - | - | 65-80 | - |
+
+---
+1. When there is no obvious yield, use Rp0.2; otherwise use Rel.
+2. Sample width B: When B＞20mm, take B=20mm; *a is sample thickness*.
+3. Tensile test and bending test take transverse samples.