feat(i18n): manifest translation extract/merge tool + en catalog

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/test_i18n_translate.py

@@ -0,0 +1,51 @@
+import copy
+
+import pytest
+
+from tools.i18n.translate_manifest import extract_en_catalog, merge_catalog
+
+MANIFEST = {
+    "clips": [
+        {"id": "cosmos", "strings": {"en": {
+            "detected.star": ["star", "young star"],
+            "measure.distance": "≈7,500 ly",
+        }}},
+    ]
+}
+
+
+def test_extract_pulls_every_en_string():
+    cat = extract_en_catalog(MANIFEST)
+    assert cat == {"cosmos": {"detected.star": ["star", "young star"], "measure.distance": "≈7,500 ly"}}
+
+
+def test_merge_writes_lang_and_leaves_en():
+    m = copy.deepcopy(MANIFEST)
+    cat = {"cosmos": {"detected.star": ["estrella", "estrella joven"], "measure.distance": "≈7.500 al"}}
+    merge_catalog(m, "es", cat)
+    s = m["clips"][0]["strings"]
+    assert s["en"]["measure.distance"] == "≈7,500 ly"   # en untouched
+    assert s["es"]["detected.star"] == ["estrella", "estrella joven"]
+
+
+def test_merge_is_idempotent():
+    m = copy.deepcopy(MANIFEST)
+    cat = {"cosmos": {"detected.star": ["estrella", "estrella joven"], "measure.distance": "≈7.500 al"}}
+    merge_catalog(m, "es", cat)
+    once = copy.deepcopy(m)
+    merge_catalog(m, "es", cat)
+    assert m == once
+
+
+def test_merge_rejects_tier_length_mismatch():
+    m = copy.deepcopy(MANIFEST)
+    bad = {"cosmos": {"detected.star": ["estrella"], "measure.distance": "≈7.500 al"}}  # 1 tier vs en's 2
+    with pytest.raises(ValueError):
+        merge_catalog(m, "es", bad)
+
+
+def test_merge_rejects_type_mismatch():
+    m = copy.deepcopy(MANIFEST)
+    bad = {"cosmos": {"detected.star": "estrella", "measure.distance": "≈7.500 al"}}  # str vs en's list
+    with pytest.raises(ValueError):
+        merge_catalog(m, "es", bad)