test(drift): flag unreachable statements and raise the call-argument floor (t62 F2)

Two gate gaps let the t62 findings ship, and both are closed here.

A pure-AST unreachable-statement pass (scan(): pass 6, entry point
scan_unreachable()): in every statement block, a statement after
return/raise/continue/break can never run. Per-block on purpose — an `else`, an
except handler or a nested function is a different block and not dead, so the
pass stays signal. Red proof: the pre-fix connection.py, saved from HEAD, is
flagged as `connection.py:1113: unreachable-statement: return at line 1110 ends
this block`; the live tree is clean. A new counter (statement_blocks, floor 500
of ~1102) keeps the "no findings" verdict from being a pass that stopped
parsing.

The call-argument floor was 20 while the walk counted 46, so deleting a
flow-display owner from HA_CALL_OWNERS did not trip it. It is 44 now, and the
suite proves the trip: removing async_show_menu yields 40 checked arguments and
`only 40 call_args (floor: 44)`. Measured removals: show_form 25, abort 38,
show_menu 40, create_entry 41, update_entry 41 all violate; the
single-call-site async_update_reload_and_abort (45) is the one owner a count
floor cannot watch, which is why the floor sits two below the count.

Also (t62 nit a): the two comments that pinned the t40 entity-attribute finding
to ``media_player.py:828`` now name the file and the attribute instead — the
line had rotted to an unrelated property.

tests/test_ha_api_drift.py

@@ -381,3 +381,102 @@ def test_the_real_ha_matrix_covers_every_entity_class_in_the_tree():
         f"entity classes never exercised against real HA: {sorted(uncovered)} — "
         f"add them to _REAL_HA_MATRIX"
     )
+
+
+# ------------------------------------------------- t62: dead code and the floor
+#
+# Both defects pinned below shipped while every other gate was green:
+# connection.py carried a duplicated copy of the label-drain body AFTER its
+# `return cached` (valid Python, dead, invisible to this sweep), and the
+# call-argument floor sat at 20 while the counts had moved to ~46, so deleting a
+# flow-display API owner from HA_CALL_OWNERS did not trip it.
+
+#: t62 F2: the shape that shipped — a bare docstring plus the whole drain left
+#: after `return cached`, inside the same method. Line 6 is the dead statement.
+UNREACHABLE_PRE_FIX = (
+    "class Sweep:\n"
+    "    def labels(self, requests):\n"
+    "        cached = {}\n"
+    "        return cached\n"
+    "\n"
+    '        """Start at most one label fetch per watchdog cycle."""\n'
+    "        if not requests:\n"
+    "            return\n"
+    "        requests.discard(min(requests))\n"
+)
+
+
+def test_the_sweep_flags_the_pre_fix_unreachable_body(tmp_path):
+    """t62 F2 red proof: the duplicated drain body after `return cached` is dead."""
+    (tmp_path / "dead_sweep.py").write_text(UNREACHABLE_PRE_FIX, encoding="utf-8")
+
+    findings = ha_api_drift.scan_unreachable(tmp_path)
+
+    assert [(finding.path, finding.kind) for finding in findings] == [
+        ("dead_sweep.py", "unreachable-statement")
+    ], findings
+    assert findings[0].lineno == 6  # the dead docstring, not the return
+
+
+def test_every_terminal_statement_kind_is_flagged(tmp_path):
+    """`return`, `raise`, `continue` and `break` all end a block (t62 F2)."""
+    (tmp_path / "terminals.py").write_text(
+        "def a():\n"
+        "    return 1\n"
+        "    x = 1\n"
+        "\n"
+        "\n"
+        "def b():\n"
+        "    raise SystemExit(1)\n"
+        "    y = 2\n"
+        "\n"
+        "\n"
+        "def c(items):\n"
+        "    for item in items:\n"
+        "        continue\n"
+        "        z = 3\n"
+        "    while True:\n"
+        "        break\n"
+        "        w = 4\n",
+        encoding="utf-8",
+    )
+
+    findings = ha_api_drift.scan_unreachable(tmp_path)
+
+    assert [finding.kind for finding in findings] == ["unreachable-statement"] * 4, findings
+
+
+def test_the_production_tree_has_no_unreachable_statements():
+    """The gate itself: dead code is a finding, so it cannot ship silently."""
+    assert ha_api_drift.scan_unreachable() == []
+
+
+def test_the_unreachable_pass_walks_real_statement_blocks():
+    """The floor proves "no findings" is not a pass that stopped parsing."""
+    report = ha_api_drift.scan()
+
+    assert report.statement_blocks >= ha_api_drift.FLOORS["statement_blocks"]
+
+
+def test_removing_a_flow_display_owner_trips_the_call_argument_floor(monkeypatch):
+    """t62: the floor must notice an API OWNER going away, not just a bad walk."""
+    _require_installed_homeassistant()
+
+    intact = ha_api_drift.scan()
+    assert intact.floor_violations() == []
+
+    reduced = dict(ha_api_drift.HA_CALL_OWNERS)
+    del reduced["async_show_menu"]  # the t57 UNIT 0a owner: 6 checked arguments
+    monkeypatch.setattr(ha_api_drift, "HA_CALL_OWNERS", reduced)
+
+    fewer = ha_api_drift.scan()
+
+    assert fewer.call_args < intact.call_args
+    assert fewer.call_args < ha_api_drift.FLOORS["call_args"], (
+        f"removing async_show_menu left {fewer.call_args} checked arguments, "
+        f"still at or above the floor of {ha_api_drift.FLOORS['call_args']} — "
+        "the flow-display owners are not load-bearing"
+    )
+    assert any("call_args" in line for line in fewer.floor_violations()), (
+        fewer.floor_violations()
+    )