PLI: return the 7-byte location object, bound every proactive chain

The PLI answer used the 5-byte form 13 05 <MCC/MNC> <LAC> with LAC 0000
and no Cell ID.  That is the *Network Rejection event download* form
(TS 31.111 8.19.1); a PLI location for GERAN is 7 bytes - MCC/MNC, LAC
and Cell ID.  A card applet that re-reads its location (the Alfa
MultiIMSI applet, after a *LOCI status change) treated it as empty and
re-requested PLI on every STATUS tick.

The default is now 13 07 00F110 0001 0001: PLMN 001/01 (the test
network), LAC 0001, Cell ID 0001.  _build_tr injects it after the
Result; the TR data is pinned by a test.

While verifying a live PLI, the manual /api/status-poll chain turned
out to be unbounded: it looped on the PLI storm while holding
_CARD_LOCK, so the request never returned and every card operation
waited.  _handle_proactive_chain's max_rounds now defaults to
_POLL_CHAIN_MAX (the background poll always passed it; the manual poll,
ENVELOPE, menu and TP chains did not), and the manual poll passes it
explicitly.  A card that re-queues a command can no longer wedge the
card lock from any call site.

Tests: the PLI default + the built TR, the default chain bound and the
manual-poll call pin.  1061 Python + 1069 frontend; sw cache simple-v477.

tests/test_poll.py

@@ -201,6 +201,20 @@ class TestProactiveChainOwnership(unittest.TestCase):
         S._handle_proactive_chain(scc, '910b', max_rounds=3)
         self.assertEqual(len(self._fetches(scc)), 3)
 
+    def test_every_chain_call_is_bounded_by_default(self):
+        # v3.37.0: the bound is the default, not only the background poll's
+        # choice - a chatty card must not wedge any call site (the manual
+        # STATUS poll and the ENVELOPE chain used to loop forever)
+        scc = FakeChattyScc()
+        S._handle_proactive_chain(scc, '910b')
+        self.assertEqual(len(self._fetches(scc)), S._POLL_CHAIN_MAX)
+
+    def test_the_manual_status_poll_passes_the_bound(self):
+        import inspect
+        src = inspect.getsource(S.PysimHandler._do_POST)
+        branch = src.split("'/api/status-poll'", 1)[1].split('elif self.path', 1)[0]
+        self.assertIn('max_rounds=_POLL_CHAIN_MAX', branch)
+
     def test_the_chain_stops_when_a_run_owns_the_card(self):
         scc = FakeChattyScc()
         S._TEST_RUNNING = True