merge: sync Rongsong's scheduler-framework into chatbot

Full merge of origin/scheduler-framework (scheduler-core restructure,
failover-adoption, WAL_JOB_DISPATCH, apiserver backend health/heartbeat,
build-time versioning, bug-1673/1676/1678/1679/1680).

Conflict resolution:
- scheduler: adopt Rongsong's scheduler-core architecture (driver loop,
  queue project/picker fields, resource bug-1569 fix)
- worker/controller_connector.c: keep Rongsong's reconnect/rejoin
  structure, PORT our bug-1509 resend_job_status onto the rejoin success
  path (his reconnect didn't re-report job state)
- apiserver backend: take Rongsong's health/heartbeat (supersedes our
  e505066 circuit breaker)
- group.c: keep our bug-1513 comment
- misc: take theirs for additive fixes (go_build versioning,
  test_group.c, persist.c RUSAGE_UPDATE, FilterRows bug-1680)

NOTE: our scheduler fixes (bug-1494 family dispatch-fail requeue,
PEND-reason classification) are NOT in Rongsong's branch — needs
verification/porting onto scheduler-core (separate follow-up).

Co-Authored-By: Claude <noreply@anthropic.com>

src/frontend/apiserver/backend/convert_pure.go

@@ -157,6 +157,7 @@ type rawSubmitData struct {
 	minTasks    int
 	maxTasks    int
 	startInfo   *rawStartInfo
+	fromHost    string
 }
 
 // rawHostReason mirrors the C xce_host_reason_t (one host-level PEND reason).
@@ -283,6 +284,7 @@ func rawJobToModel(r rawJobData) *models.JobInfo {
 		info.ResReq = s.resReq
 		info.NumProcessors = s.minTasks
 		info.MaxNumProcessors = s.maxTasks
+		info.FromHost = s.fromHost
 		if s.startInfo != nil {
 			si := s.startInfo
 			info.Command = si.cmdline