A-batch admin-plane fixes: rusage unit name, XCE_JOBID identity, select WARN, CLI env, docs

rusage collection (merge cb0c7fe9 regression, root cause of 0 counters):
- collect_job_rusages builds the systemd unit name with
  make_job_sd_unit_name (four-segment fmt_jobid_ex form) instead of a bare
  %lu of the packed uint64, so the D-Bus property lookups hit the real
  per-job unit again. E2E on t1: DONE job reports max_mem/avg_mem/cpu_time
  non-zero (previously all 0).

XCE_JOBID written identity:
- exdata sets XCE_JOBID via fmt_jobid (four-segment
  cluster-apiserver-timestamp-seq) instead of a bare packed decimal;
  XCE_JOBINDEX handling unchanged.
- xrun parses XCE_JOBID with parse_jobid (accepts the four-segment form);
  a bare decimal no longer round-trips through the written identity.
- E2E on t1: job sees XCE_JOBID=<submit id>; xrun remote-start round-trip
  to another host matches the job.

select WARN (silent degradation):
- parse_resreq_primary WARNs when a select references an unregistered
  resource ("...references an unregistered resource -- dropping the select
  and skipping any rusage[] clause of this primary") instead of failing
  silently; scheduler log shows the WARN on t1 and the job schedules
  without the constraint.

CLI env handling (unit-tested; subEnvVars is not flag-bound so this is
not reachable from the production CLI):
- getEnvironmentVariables keeps B=b=c (split at first '=') and warns +
  drops a bare key or an '=value' fragment instead of silently mis-parsing.

Docs:
- src/docs/xce.md: document the dead-clause semantics (select/rusage
  primary drop behavior) matching the WARN.

bug-1972 (test-only UAF): test_job_live_gc asserted job destruction by
reading refcount from the freed job; rewrite the assertion to observe
destruction without touching freed memory. controller_unit_test is green
again (1354 tests).

Regenerate 3 repl_trace_baseline fixtures whose baselines shifted with the
select-WARN logging; replay tests green.

Spec naming: external-license-resources design.md/brief.md fix the
self-referential daemon-name note (old drafts said xceextresd/extresd).

Verified on t1: rusage_burn job (counters non-zero in DONE), echo_env job
(four-segment XCE_JOBID), select[nosuchres] job (WARN + schedules),
xrun t2 remote-start round-trip, CLI env unit tests, xcelib 762 /
controller 1354 / worker exdata 8+11 / sched repl_trace 4+14+4+10+17
tests green.

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

src/frontend/xcecli/cmd/jobs/submit_test.go

@@ -1,8 +1,10 @@
 package jobs
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -133,6 +135,48 @@ func TestSubmitHelpShowsArrayForms(t *testing.T) {
 	}
 }
 
+// getEnvironmentVariables must keep entries whose value contains '=' (the
+// apiserver splits at the FIRST '=', so A=b=c is A -> "b=c") -- dropping
+// them used to be silent data loss. A nameless or '='-less entry cannot
+// become a map key, so it is warned about and dropped.
+func TestGetEnvironmentVariables_KeepsMultiEqualSign(t *testing.T) {
+	js := NewJobSubmitter(nil)
+	js.subEnvVars = []string{"A=1", "B=b=c", "C=", "=novalue", "novalue"}
+
+	r, w, pipeErr := os.Pipe()
+	if pipeErr != nil {
+		t.Fatalf("pipe: %v", pipeErr)
+	}
+	old := os.Stdout
+	os.Stdout = w
+	done := make(chan string)
+	go func() {
+		var buf bytes.Buffer
+		_, _ = io.Copy(&buf, r)
+		done <- buf.String()
+	}()
+	got := js.getEnvironmentVariables()
+	os.Stdout = old
+	_ = w.Close()
+	warn := <-done
+
+	want := []string{"A=1", "B=b=c", "C="}
+	if len(got) != len(want) {
+		t.Fatalf("env = %q, want %q", got, want)
+	}
+	for i := range want {
+		if got[i] != want[i] {
+			t.Errorf("env[%d] = %q, want %q", i, got[i], want[i])
+		}
+	}
+	if !strings.Contains(warn, "=novalue") || !strings.Contains(warn, "warning:") {
+		t.Errorf("warning output = %q, want it to name the nameless entry", warn)
+	}
+	if !strings.Contains(warn, "novalue") {
+		t.Errorf("warning output = %q, want it to name the '='-less entry", warn)
+	}
+}
+
 // Attach marks the terminal-attach kind of TTY job so the worker may reap
 // ttyd when no client ever connects; --browse keeps the web-viewed
 // semantics and must not set it.