fix: the lane/program guard compared every section, not just programs (4295)

`test_every_lane_gets_a_program` asserted
`set(cp.sections()) - {"supervisord"} == expected`, so it failed the moment
the generated config grew non-program sections. b09ee87 added three — the
control socket that lets `supervisorctl` reach supervisord — and the
property the test exists for had not moved at all: every lane still has a
program and no program is not a lane.

Now compared over `program:` sections only, both directions. A guard that
fires on a correct change is one people learn to edit rather than read, which
costs more than it catches.

I reported b09ee87 as green off runs 7328 and 7330 and did not look at 7329,
which was red on this. The image itself smoked clean — that part was true —
but "green" was a claim about the commit and I checked two of its three runs.
Earlier in this session I had been reading all three every time.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LVjrnpQjRgHdvq95rASoiR

tests/test_gen_supervisord.py

@@ -39,10 +39,19 @@ def test_it_is_valid_ini_with_a_supervisord_section():
 
 def test_every_lane_gets_a_program():
     """One image carries every lane since step 6, so nothing is conditional.
-    A lane in LANES with no program is a queue with no consumer."""
+    A lane in LANES with no program is a queue with no consumer.
+
+    Compared over the `program:` sections ONLY, both directions: no lane
+    without a program, and no program that is not a lane. It used to compare
+    every section minus `[supervisord]`, which made it fail the moment the
+    config grew non-program plumbing — the control socket did exactly that,
+    and the property it exists for had not moved at all. A guard that fires on
+    a correct change is one people learn to edit rather than read.
+    """
     cp = _parse()
+    programs = {s for s in cp.sections() if s.startswith("program:")}
     expected = {"program:web"} | {f"program:{lane.name}" for lane in LANES}
-    assert set(cp.sections()) - {"supervisord"} == expected
+    assert programs == expected
 
 
 def test_the_ml_lane_runs_even_though_it_ships_disabled():