feat(channel-monitor): request templates with snapshot apply + headers/body override

Problem:
Upstream channels can reject monitor probes based on client fingerprint
(e.g. "only Claude Code clients allowed"). The monitor had no way to
customize the outgoing request to bypass such restrictions.

Solution:
Introduce reusable request templates that carry extra_headers plus an
optional body override; monitors reference a template and receive a
snapshot copy on apply. Template edits do NOT auto-propagate — users
must click "apply to associated monitors" to refresh snapshots, so a
bad template edit cannot instantly break all production monitors.

Data model (migration 112):
- channel_monitor_request_templates: id, name, provider, description,
  extra_headers jsonb, body_override_mode ('off'|'merge'|'replace'),
  body_override jsonb. Unique (provider, name).
- channel_monitors: +template_id (FK, ON DELETE SET NULL), +extra_headers,
  +body_override_mode, +body_override (the three runtime snapshot fields).

Checker (channel_monitor_checker.go):
- callProvider + runCheckForModel accept a CheckOptions carrying the
  snapshot fields. mergeHeaders applies user headers on top of adapter
  defaults (forbidden list: Host / Content-Length / Transfer-Encoding /
  Connection / Content-Encoding).
- buildRequestBody:
    off     -> adapter default body
    merge   -> shallow-merge over default; per-provider deny list
               (model/messages/contents) protects the challenge contract
    replace -> user body verbatim
- Replace mode skips challenge validation; instead HTTP 2xx + non-empty
  extracted response text = operational, empty = failed.
- 4 new unit tests cover all three modes + replace/empty-response case.

Admin API:
- /admin/channel-monitor-templates CRUD + /:id/apply (overwrite snapshot
  on all template_id=id monitors, returns affected count).
- channel_monitor request/response DTOs gain the 4 new fields.

Frontend:
- channelMonitorTemplate.ts API client.
- MonitorAdvancedRequestConfig.vue shared component for headers textarea
  + body mode radio + body JSON editor; used by both template and monitor
  forms.
- MonitorTemplateManagerDialog.vue: provider tabs, list/create/edit/
  delete/apply, live "associated monitors" count per row.
- MonitorFiltersBar: new 模板管理 button next to 新增监控.
- MonitorFormDialog: collapsible 高级 section with template dropdown
  (filtered by form.provider, clears on provider change) + embedded
  AdvancedRequestConfig. Picking a template copies its fields into the
  form (snapshot semantics mirrored on the client).
- i18n zh/en entries for all new copy.

chore: bump version to 0.1.114.32

backend/internal/handler/handler.go

@@ -6,33 +6,34 @@ import (
 
 // AdminHandlers contains all admin-related HTTP handlers
 type AdminHandlers struct {
-	Dashboard             *admin.DashboardHandler
-	User                  *admin.UserHandler
-	Group                 *admin.GroupHandler
-	Account               *admin.AccountHandler
-	Announcement          *admin.AnnouncementHandler
-	DataManagement        *admin.DataManagementHandler
-	Backup                *admin.BackupHandler
-	OAuth                 *admin.OAuthHandler
-	OpenAIOAuth           *admin.OpenAIOAuthHandler
-	GeminiOAuth           *admin.GeminiOAuthHandler
-	AntigravityOAuth      *admin.AntigravityOAuthHandler
-	Proxy                 *admin.ProxyHandler
-	Redeem                *admin.RedeemHandler
-	Promo                 *admin.PromoHandler
-	Setting               *admin.SettingHandler
-	Ops                   *admin.OpsHandler
-	System                *admin.SystemHandler
-	Subscription          *admin.SubscriptionHandler
-	Usage                 *admin.UsageHandler
-	UserAttribute         *admin.UserAttributeHandler
-	ErrorPassthrough      *admin.ErrorPassthroughHandler
-	TLSFingerprintProfile *admin.TLSFingerprintProfileHandler
-	APIKey                *admin.AdminAPIKeyHandler
-	ScheduledTest         *admin.ScheduledTestHandler
-	Channel               *admin.ChannelHandler
-	ChannelMonitor        *admin.ChannelMonitorHandler
-	Payment               *admin.PaymentHandler
+	Dashboard              *admin.DashboardHandler
+	User                   *admin.UserHandler
+	Group                  *admin.GroupHandler
+	Account                *admin.AccountHandler
+	Announcement           *admin.AnnouncementHandler
+	DataManagement         *admin.DataManagementHandler
+	Backup                 *admin.BackupHandler
+	OAuth                  *admin.OAuthHandler
+	OpenAIOAuth            *admin.OpenAIOAuthHandler
+	GeminiOAuth            *admin.GeminiOAuthHandler
+	AntigravityOAuth       *admin.AntigravityOAuthHandler
+	Proxy                  *admin.ProxyHandler
+	Redeem                 *admin.RedeemHandler
+	Promo                  *admin.PromoHandler
+	Setting                *admin.SettingHandler
+	Ops                    *admin.OpsHandler
+	System                 *admin.SystemHandler
+	Subscription           *admin.SubscriptionHandler
+	Usage                  *admin.UsageHandler
+	UserAttribute          *admin.UserAttributeHandler
+	ErrorPassthrough       *admin.ErrorPassthroughHandler
+	TLSFingerprintProfile  *admin.TLSFingerprintProfileHandler
+	APIKey                 *admin.AdminAPIKeyHandler
+	ScheduledTest          *admin.ScheduledTestHandler
+	Channel                *admin.ChannelHandler
+	ChannelMonitor         *admin.ChannelMonitorHandler
+	ChannelMonitorTemplate *admin.ChannelMonitorRequestTemplateHandler
+	Payment                *admin.PaymentHandler
 }
 
 // Handlers contains all HTTP handlers