Add regression tests for triple-chained prefixes and chain+suffix

PR review flagged that the current tests only cover the narrowest case
(a single prefix phrase repeated twice). Add two stronger guards for the
exact code path #208's fix touches: 3+ chained repeats, and a repeated
chain immediately followed by a suffix (the prefix-run absorption loop
and the suffix-boundary loop share the same index variable, so this
combination is worth pinning down explicitly).

Author: derek73

tests/test_prefixes.py

@@ -317,6 +317,23 @@ def test_repeated_prefix_chain_van_der(self) -> None:
         self.m(hn.first, "Charles", hn)
         self.m(hn.last, "van der van der Berg", hn)
 
+    def test_triple_repeated_prefix_chain(self) -> None:
+        # a stronger regression guard than the 2-repeat cases above: the
+        # contiguous-prefix absorption loop should chain any number of
+        # repeats, not just handle exactly two
+        hn = HumanName("Juan de la de la de la Vega")
+        self.m(hn.first, "Juan", hn)
+        self.m(hn.last, "de la de la de la Vega", hn)
+
+    def test_repeated_prefix_chain_followed_by_suffix(self) -> None:
+        # the prefix-run absorption loop and the suffix-boundary loop share
+        # the same index variable, so a repeated chain immediately
+        # followed by a suffix is worth pinning down explicitly
+        hn = HumanName("Juan de la de la Vega Jr.")
+        self.m(hn.first, "Juan", hn)
+        self.m(hn.last, "de la de la Vega", hn)
+        self.m(hn.suffix, "Jr.", hn)
+
     # --- safety: excluded / ambiguous particles are unchanged ---
 
     def test_leading_von_is_unchanged(self) -> None: