feat: Kinetic Dark 设计语言 + Lucide 图标迁移 + 首页轻量个性化

- 建立 Lucide 子集 iconfont（49 字形），全站 emoji 替换为 fc-icon 组件
- 重塑 Design Token（冷中性近黑底 + Volt 荧光绿 #B6F24E），消除硬编码颜色
- 首页登录后个性化：我的计划 / 我的收藏 / 今日推荐（纯前端复用现有 API）
- 后端 DEFAULT_EMOJI→Lucide 名，PALETTE 对齐 Kinetic Dark 语义色板
- 修复 person-standing 缺失字形；14 个官方组合 seed emoji 全部映射到现有字形

miniprogram/assets/fonts/fc-icon.json

@@ -0,0 +1,51 @@
+{
+    "zap": 61697,
+    "x-circle": 61698,
+    "user": 61699,
+    "trophy": 61700,
+    "trending-up": 61701,
+    "trash-2": 61702,
+    "target": 61703,
+    "star": 61704,
+    "sparkles": 61705,
+    "sliders-horizontal": 61706,
+    "share-2": 61707,
+    "settings": 61708,
+    "search": 61709,
+    "rotate-cw": 61710,
+    "refresh-cw": 61711,
+    "plus": 61712,
+    "play": 61713,
+    "person-standing": 61714,
+    "medal": 61715,
+    "log-out": 61716,
+    "layout-grid": 61717,
+    "layers": 61718,
+    "info": 61719,
+    "image": 61720,
+    "home": 61721,
+    "heart": 61722,
+    "grid-2x2": 61723,
+    "folder-open": 61724,
+    "flame": 61725,
+    "filter": 61726,
+    "dumbbell": 61727,
+    "download": 61728,
+    "clock": 61729,
+    "clipboard-list": 61730,
+    "circle-x": 61731,
+    "chevron-right": 61732,
+    "chevron-down": 61733,
+    "check": 61734,
+    "check-circle": 61735,
+    "calendar": 61736,
+    "bookmark": 61737,
+    "bike": 61738,
+    "bell": 61739,
+    "award": 61740,
+    "arrow-right": 61741,
+    "arrow-left": 61742,
+    "alert-circle": 61743,
+    "activity": 61744,
+    "accessibility": 61745
+}