feat(postcard): profile country, country_from, per-user card number uniqueness, public page overhaul - Profile: add country field for default origin country - Postcard: add country_from field, auto-fill from profile.country on create - card_number uniqueness: change from global to per-user (profile_id + card_number) - Public pages: remove card_number display, only show cards with image_front - Public pages: show country as from→to format - Index page: no time display, add register button, fix lightbox with prev/next - Infinite scroll: add /api/public/cards endpoints and IntersectionObserver - Internal pages: update postcards list/detail for country_from display - i18n: add profiles.country_ph, pc_form.country_from, pc_detail.route

app/locales/zh.json

@@ -6,6 +6,7 @@
   "index.title": "星笺",
   "index.subtitle": "来自世界各地的明信片",
   "index.go_login": "登录",
+  "index.go_register": "注册",
   "index.empty": "暂无公开明信片",
   "nav.profiles": "Profile",
   "nav.settings": "设置",
@@ -64,6 +65,7 @@
   "profiles.total": "总计",
   "profiles.countries": "国家",
   "profiles.notes_ph": "备注（仅自己可见）",
+  "profiles.country_ph": "国家",
   "profiles.save": "保存",
   "profiles.created_at": "创建于",
   "profiles.view": "查看",
@@ -96,6 +98,7 @@
   "pc_detail.status": "状态",
   "pc_detail.recipient": "收件人",
   "pc_detail.country": "国家/地区",
+  "pc_detail.route": "路线",
   "pc_detail.send_time": "寄出时间",
   "pc_detail.arrival_time": "到达时间",
   "pc_detail.sender": "发件人",
@@ -112,6 +115,7 @@
   "pc_form.status": "状态",
   "pc_form.recipient": "收件人",
   "pc_form.country": "国家/地区",
+  "pc_form.country_from": "寄出地",
   "pc_form.send_time": "寄出时间",
   "pc_form.arrival_time": "到达时间",
   "pc_form.sender": "发件人",