P7: restore agent node type, agent heartbeat expiry, build-version injection, remove log/history/xray-metrics modules, optional sub port

- nodes: port node-type (traditional/agent) picker back from web-src into
  the embedded frontend; backend annotates NodeView.nodeType from
  agent_nodes bindings; fix agent-node update path (skip reachability
  probe and apiToken requirement for agent-managed nodes); restore i18n
  keys in all 13 locales; install command now uses the Gitea mirror
- jobs: expire agent-bound nodes whose agent_nodes.last_seen is older
  than max(3x heartbeat interval, 120s) = 180s; last_seen=0 (never
  registered) is left untouched; transitions reuse UpdateHeartbeat +
  node event broadcast
- config: GetBaseVersion honors ldflags-injected buildVersion; release
  builds inject 3.7.0-agent.1 so the panel no longer reports a phantom
  update against the Gitea release tag
- logger/server: remove the three log viewers (panel/xray/amneziawg),
  their API endpoints and the 10240-entry in-memory log buffer; file
  logging via lumberjack unchanged; tests assert via a new optional
  logger hook instead of the removed buffer
- server: remove system history and xray metrics modules end to end
  (endpoints, sampling appends in RefreshStatus, per-minute persist
  cron, gob snapshot/restore, XrayMetricsService); realtime status and
  per-node history are untouched
- settings: subPort may be 0/unset - subscription links are generated
  without a port while the subscription service keeps binding the
  default 2096; the settings form declares the cleared state via
  onNumber's new onClear option instead of snapping back to 1

frontend/src/generated/zod.ts

@@ -98,7 +98,7 @@ export const AllSettingSchema = z.object({
   subKeyFile: z.string(),
   subListen: z.string(),
   subPath: z.string(),
-  subPort: z.number().int().min(1).max(65535),
+  subPort: z.number().int().min(0).max(65535),
   subProfileUrl: z.string(),
   subRoutingRules: z.string(),
   subShowIdentityOnAllLinks: z.boolean(),
@@ -214,7 +214,7 @@ export const AllSettingViewSchema = z.object({
   subKeyFile: z.string(),
   subListen: z.string(),
   subPath: z.string(),
-  subPort: z.number().int().min(1).max(65535),
+  subPort: z.number().int().min(0).max(65535),
   subProfileUrl: z.string(),
   subRoutingRules: z.string(),
   subShowIdentityOnAllLinks: z.boolean(),