Add key-name validation mirroring the keypad model

Rejects unknown names in the server rather than letting them reach QMP as an
error. A test parses keypad_key_names out of qemu/py32f071.c and fails if the
lists drift, so adding a key to the model cannot silently leave the web UI
behind.

PTT is deliberately absent: the model wires it separately on GPIOC, so the press
property rejects the name.

tools/test_uvk5_keys.py

@@ -0,0 +1,52 @@
+#!/usr/bin/env python3
+"""Unit tests for key-name validation."""
+import os
+import re
+import unittest
+
+from uvk5_keys import KEYS, is_valid, normalise
+
+
+class TestKeys(unittest.TestCase):
+    def test_matches_the_model_key_list(self):
+        # keypad_key_names in qemu/py32f071.c
+        self.assertEqual(set(KEYS), {
+            "MENU", "UP", "DOWN", "EXIT", "F", "STAR",
+            "0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
+            "SIDE1", "SIDE2",
+        })
+
+    def test_stays_in_sync_with_the_machine_model(self):
+        """Read the real list out of py32f071.c so the two cannot drift.
+
+        If someone adds a key to the model, this fails until KEYS is updated --
+        which beats discovering it as a QMP error at runtime.
+        """
+        src = os.path.join(os.path.dirname(os.path.abspath(__file__)),
+                           os.pardir, "qemu", "py32f071.c")
+        text = open(src).read()
+        block = re.search(
+            r"keypad_key_names\[[^\]]*\]\s*=\s*\{(.*?)\};", text, re.S)
+        self.assertIsNotNone(block, "could not find keypad_key_names in the model")
+        names = set(re.findall(r'"([^"]+)"', block.group(1)))
+        self.assertEqual(names, set(KEYS))
+
+    def test_ptt_is_not_offered(self):
+        # The keypad model has no PTT line; qom-set would error on it.
+        self.assertFalse(is_valid("PTT"))
+
+    def test_normalise_is_case_insensitive_and_strips(self):
+        self.assertEqual(normalise("menu"), "MENU")
+        self.assertEqual(normalise("  up  "), "UP")
+        self.assertTrue(is_valid("menu"))
+
+    def test_rejects_unknown(self):
+        self.assertFalse(is_valid("BANANA"))
+
+    def test_rejects_empty_and_none(self):
+        self.assertFalse(is_valid(""))
+        self.assertFalse(is_valid(None))
+
+
+if __name__ == "__main__":
+    unittest.main()