feat: port remaining Vue UI surfaces with full backend support

Backend additions:
- New GORM models: NotifyChannel, PlayProfile (with PIN hashing).
- NotifyChannelService: multi-channel CRUD + unified dispatcher
  supporting Telegram / Bark / WeChat / Webhook with optional
  per-channel event filtering.
- PlayProfileService: per-user 'viewing personas' with
  content-rating gates, library scoping, PIN protection, and
  player defaults (autoplay, skip-intro, audio/subtitle prefs).
- New endpoints:
    GET    /admin/notify/channels           list
    POST   /admin/notify/channels           create
    PUT    /admin/notify/channels/:id       update
    DELETE /admin/notify/channels/:id       delete
    POST   /admin/notify/channels/:id/test  send test
    GET    /play-profiles                   list (admin: ?all=true)
    POST   /play-profiles                   create
    PUT    /play-profiles/:id               update
    DELETE /play-profiles/:id               delete
    GET    /media/recent                    home page rail
    GET    /media/stats                     library composition
    GET    /watch-history                   list
    GET    /watch-history/stats             aggregate
    GET    /watch-history/continue          continue-watching rail
    DELETE /watch-history[?media_id=]       clear
    DELETE /watch-history/:id               remove one
    GET    /discover/sections               available rails
    GET    /discover/feed?sections=a,b      multi-section TMDb fetch
    GET    /system/info                     name/version/runtime
    GET    /system/status                   uptime/cpu/mem/disk
    GET    /system/scheduler                read-only scheduler view
    GET    /stats/overview                  counts only
    GET    /stats/trend                     daily plays
    GET    /stats/top-content               most played
    GET    /stats/libraries                 per-library size
    GET    /stats/monitor                   live hardware

Frontend additions:
- New API helpers: notify_channels, play_profiles, history,
  stats_extra, media_extra, discover_extra, system.
- ProfileManagementPage (/play-profiles): full CRUD form with
  PIN management, library scoping, language preferences.
- NotifyChannelsPage (/notify-channels, admin): typed config
  forms per channel type + per-channel test action.
- SettingsPage (/settings, admin): grouped key/value editor
  covering General, Organize/Scrape, Adult, qBittorrent.
- Layout sidebar links and App.tsx routes wired for all three.

web/src/components/Layout.tsx

@@ -2,6 +2,7 @@ import { useEffect, useState } from 'react'
 import { Link, NavLink, Outlet, useNavigate } from 'react-router-dom'
 import {
   Activity,
+  Bell,
   Cast,
   Clock,
   CloudDownload,
@@ -22,8 +23,10 @@ import {
   Rss,
   Search,
   Settings,
+  Sliders,
   Sparkles,
   Trash2,
+  UserCog,
   Wrench,
   Library as LibraryIcon,
   User as UserIcon,
@@ -98,6 +101,7 @@ export function Layout() {
             账号
           </div>
           <SidebarLink to="/profile" icon={<UserIcon size={18} />} label="个人资料" />
+          <SidebarLink to="/play-profiles" icon={<UserCog size={18} />} label="观影 Profile" />
 
           {user?.role === 'admin' && (
             <>
@@ -113,6 +117,8 @@ export function Layout() {
               <SidebarLink to="/api-configs" icon={<KeyRound size={18} />} label="API 配置" />
               <SidebarLink to="/strm" icon={<Link2 size={18} />} label="STRM 管理" />
               <SidebarLink to="/tools" icon={<Wrench size={18} />} label="运维工具" />
+              <SidebarLink to="/notify-channels" icon={<Bell size={18} />} label="通知渠道" />
+              <SidebarLink to="/settings" icon={<Sliders size={18} />} label="系统设置" />
               <SidebarLink to="/recycle" icon={<Trash2 size={18} />} label="回收站" />
               <SidebarLink to="/admin" icon={<Settings size={18} />} label="管理后台" />
             </>