feat(ticket): replace the after-sale flow with a general ticket system

The old 售后 flow was an order-refund appendage: tickets were hard-bound to an
order number, users could only file them from 「我的订单」against a paid order,
and the admin action bottomed out at 「标记订单已退款」. It could not carry
account questions or feature requests that have nothing to do with an order.

Replace it with a general ticket system modelled on 魔方财务云's idcsmart_ticket:
title + department + description are required, linking an order is optional
(user's own paid orders only). Add departments, custom statuses, preset replies
and internal admin notes as four configuration surfaces. Conversation history
moves off the ticket row's JSON log into dedicated ticket_reply rows, which
unlocks quoted replies. Front end gets a 工单中心 panel under 我的服务; back end
moves from 支付中心 → 售后服务 to users.php → 工单管理.

Per CLAUDE.md's rewrite-over-compatibility rule: drop the old table, build new
ones, delete the old code. No dual paths, no data migration. The upstream
plugin's upstream/downstream delivery and internal-ticket conversion are
deliberately left out — both are multi-provider platform concerns with no
meaning on a single WordPress site.

Data: order_aftersale becomes six aksrt_ticket* tables (ticket, ticket_reply,
ticket_status, ticket_type, ticket_prereply, ticket_note). SCHEMA_VERSION
2.6.0 -> 3.0.0. Status and department seeds are idempotent; the default status
「待接单」is flagged as non-editable.

Domain: new src/Ticket/ (13 files, all under 460 lines). Attachments reuse
UserController::rest_upload_comment_image with a ticket-specific permission
callback, mirroring the existing /report/upload-image route rather than
growing a second upload path.

Notifications go through AKSRT\Messages\Message::send() and deep-link to the
right surface; email/SMS stay out of scope since the theme's mail and SMS
stacks are separate implementations.

Refund gate opens up: marking an order refunded no longer requires an in-flight
ticket, only that the order is paid.

Also generalise a hardcoded special case in tools/audit-admin-contracts.php —
schema domain inference now reads the parent directory instead of matching
"PostList" by name, so new leaf schema files need no per-name exception.

Verification:
  php tools/audit-admin-contracts.php   exit 0, errors=0
  node --test (widget-system + admin)   664 pass / 0 fail
  php -l over all new/changed files     clean
  node --check over all JS              clean
  npm run build + build:public          clean

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

README.md

@@ -38,7 +38,7 @@ AKSRT-theme/
 │   ├── Extensions/                    # MeiliSearch / 推送 / IP / 内容审核
 │   ├── Frontend/                      # 前端渲染辅助
 │   ├── Messages/                      # 站内信 / 公告 / 举报
-│   ├── Payment/                       # 订单 / 网关 / 售后 / 物流 / 分成
+│   ├── Payment/                       # 订单 / 网关 / 物流 / 分成
 │   │   └── Gateways/                  # 支付宝 / 微信 / PayPal / Stripe
 │   ├── Settings/                      # 设置门面 + 运行时 delegates
 │   ├── Shop/                          # 商城服务 + meta box