Add name suggestion engine with API endpoint and tests

Expand services/naming.py with suggest_names() that picks random words
from a category while excluding nicknames already used in the run. Add
GET /runs/{run_id}/name-suggestions?count=10 endpoint that reads the
run's naming_scheme and returns filtered suggestions. Includes 12 unit
tests covering selection, exclusion, exhaustion, and cross-category
independence.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/tests/test_naming.py

@@ -0,0 +1,84 @@
+from unittest.mock import patch
+
+import pytest
+
+from app.services.naming import (
+    get_naming_categories,
+    get_words_for_category,
+    suggest_names,
+)
+
+MOCK_DICTIONARY = {
+    "mythology": ["Apollo", "Athena", "Loki", "Thor", "Zeus"],
+    "food": ["Basil", "Sage", "Pepper", "Saffron", "Mango"],
+    "space": ["Apollo", "Nova", "Nebula", "Comet", "Vega"],
+}
+
+
+@pytest.fixture(autouse=True)
+def _mock_dictionary():
+    with patch("app.services.naming._load_dictionary", return_value=MOCK_DICTIONARY):
+        yield
+
+
+class TestGetNamingCategories:
+    def test_returns_sorted_categories(self):
+        result = get_naming_categories()
+        assert result == ["food", "mythology", "space"]
+
+    def test_returns_empty_for_empty_dictionary(self):
+        with patch("app.services.naming._load_dictionary", return_value={}):
+            assert get_naming_categories() == []
+
+
+class TestGetWordsForCategory:
+    def test_returns_words_for_valid_category(self):
+        result = get_words_for_category("mythology")
+        assert result == ["Apollo", "Athena", "Loki", "Thor", "Zeus"]
+
+    def test_returns_empty_for_unknown_category(self):
+        assert get_words_for_category("nonexistent") == []
+
+
+class TestSuggestNames:
+    def test_returns_requested_count(self):
+        result = suggest_names("mythology", set(), count=3)
+        assert len(result) == 3
+        assert all(name in MOCK_DICTIONARY["mythology"] for name in result)
+
+    def test_excludes_used_names(self):
+        used = {"Apollo", "Athena", "Loki"}
+        result = suggest_names("mythology", used, count=10)
+        assert set(result) <= {"Thor", "Zeus"}
+        assert not set(result) & used
+
+    def test_returns_fewer_when_category_nearly_exhausted(self):
+        used = {"Apollo", "Athena", "Loki", "Thor"}
+        result = suggest_names("mythology", used, count=10)
+        assert result == ["Zeus"]
+
+    def test_returns_empty_when_category_fully_exhausted(self):
+        used = {"Apollo", "Athena", "Loki", "Thor", "Zeus"}
+        result = suggest_names("mythology", used, count=10)
+        assert result == []
+
+    def test_returns_empty_for_unknown_category(self):
+        result = suggest_names("nonexistent", set(), count=10)
+        assert result == []
+
+    def test_no_duplicates_in_suggestions(self):
+        result = suggest_names("mythology", set(), count=5)
+        assert len(result) == len(set(result))
+
+    def test_default_count_is_ten(self):
+        # food has 5 words, so we should get all 5
+        result = suggest_names("food", set())
+        assert len(result) == 5
+
+    def test_cross_category_names_handled_independently(self):
+        # "Apollo" used in mythology shouldn't affect space
+        used = {"Apollo"}
+        mythology_result = suggest_names("mythology", used, count=10)
+        space_result = suggest_names("space", used, count=10)
+        assert "Apollo" not in mythology_result
+        assert "Apollo" not in space_result