forgetest: every run starts from, and leaves, the fresh-boot idle state

A baseline pass brackets every test and bench tool: before the run the
machine is verified against the fresh-boot idle state and anything off it
is restored; after the run - pass, fail, or abort - it is restored again.
Fixed items are the resting values the boot establishes (module defaults,
forgectrl's start-up writes, the GRBL controller's init writes) and
forgectrl's idle picture (controller running with motion verified, no
diagnostic, camera and cooling engines idle); preserved items (lid lamp
level, position counters, settings map, controller mode) are captured
before and handed back after. Deviations are leftovers: in the run pane,
in the result's evidence, and on the page - attributed to the previous run
when found before, to the run itself when found after.

forgetest takes a fresh-boot reference once per boot (within ten minutes
of boot, after the supervisor settles) as the session's resting lid-lamp
level and the check on the fixed values; the values were confirmed
against a fresh boot of the dev image on the bench (step_freq rests at
28160, the controller's default tick, not the probe's 10000).

Takeover runs capture the controller-owned kernel attributes on entry and
write them back before forgectrl restarts: the bench found the kernel
tests leaving motor_lock=15 behind, which masked the supervisor's
liveness probe - no motion by construction, a false driver-wedge verdict,
the rail-off ladder, and finally motion-fault. The takeover wrapper also
waits for the supervisor to settle on both sides (moved into baseline).

Catalog consequence: none beyond the runner; the tests' own drills are
unchanged.

forgetest/tests/test_server.py

@@ -168,7 +168,9 @@ class ServerTests(unittest.TestCase):
         self.assertEqual(state["last_run"]["finished"]["result"], "PASS")
         st, rec = self.call("GET", "/result?test=fake.pass")
         self.assertEqual(st, 200)
-        self.assertEqual(rec["evidence"], {"k": 1})
+        self.assertEqual(rec["evidence"]["k"], 1)
+        # the baseline passes ran (no machine on the host: nothing to restore)
+        self.assertEqual(rec["evidence"]["baseline"], {"pre": [], "post": []})
         self.assertTrue(any("hello" in l for l in rec["log"]))
 
     def test_03_requires_and_live_gate(self):
@@ -291,7 +293,7 @@ class ServerTests(unittest.TestCase):
         log = "\n".join(state["last_run"]["log"])
         self.assertIn("takeover: pulse device free", log)
         self.assertIn("takeover: forgectrl start", log)
-        self.assertIn("takeover: forgectrl unreachable for 10 s", log)
+        self.assertIn("baseline: forgectrl unreachable for 10 s", log)
         self.assertFalse(os.path.exists(os.environ["FORGETEST_MARKER"]))
         # bench runs never touched the acceptance log
         recs = self.log.read()