fix(rawcli): Ctrl-/ key binding crashed launch ("Invalid key: c-/")

prompt_toolkit doesn't accept "c-/". Ctrl-/ is emitted as Ctrl-_ (0x1F)
by terminals, so bind "c-_" (plus "c-t" as an always-available fallback)
for the hex/binary toggle. install_key_bindings() now ignores any key
name a prompt_toolkit build rejects, so a bad key can never crash launch.
Regression test added.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_rawcli.py

@@ -326,3 +326,13 @@ class TestCompleter:
         s.protocol, s.transponder = "hf14a", "NTAG215"
         cs = self._complete(s, "help GET")
         assert any(c.text == "GET_VERSION" for c in cs)
+
+
+class TestKeyBindings:
+    def test_install_does_not_raise(self):
+        # regression: "c-/" is not a valid prompt_toolkit key and used to crash launch
+        from prompt_toolkit.key_binding import KeyBindings
+        from pm3py.cli.rawcli.entry import install_key_bindings, TOGGLE_KEYS
+        kb = KeyBindings()
+        install_key_bindings(kb, RawSession())
+        assert len(kb.bindings) >= len(TOGGLE_KEYS)