feat: propagate tag renames to articles after taxonomy save

After saving TaxonomyView, detect renamed IT/EN tags by comparing
old and new it_to_en dicts, then rewrite frontmatter of affected
articles. Status bar shows count of updated articles. Taxonomy
save failure aborts propagation. Adds pytest-qt and four unit
tests for _detect_renames.

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

1 files changed, 33 insertions, 0 deletions

diff --git a/tests/test_taxonomy.py b/tests/test_taxonomy.py
index a10531b..b5f48e9 100644
--- a/tests/test_taxonomy.py
+++ b/tests/test_taxonomy.py
@@ -2,6 +2,7 @@
 import pytest
 from pathlib import Path
 from core.taxonomy import TaxonomyModel, load_taxonomy, save_taxonomy
+from ui.taxonomy_view import TaxonomyView
 
 def _write_pair(tmp_path, it_lines, en_lines):
     it_file = tmp_path / "tags-it.txt"
@@ -41,3 +42,35 @@ def test_save_taxonomy_sorted(tmp_path):
     save_taxonomy(model, it_f, en_f)
     lines = it_f.read_text().splitlines()
     assert lines == sorted(lines)
+
+
+def test_detect_renames_en_change(qtbot):
+    old = {"linux": "linux", "vita": "life"}
+    new = {"linux": "linux", "vita": "living"}
+    it_r, en_r = TaxonomyView._detect_renames(old, new)
+    assert it_r == {}
+    assert en_r == {"life": "living"}
+
+
+def test_detect_renames_it_change(qtbot):
+    old = {"linux": "linux", "vita": "life"}
+    new = {"linux": "linux", "living": "life"}
+    it_r, en_r = TaxonomyView._detect_renames(old, new)
+    assert it_r == {"vita": "living"}
+    assert en_r == {}
+
+
+def test_detect_renames_no_change(qtbot):
+    old = {"linux": "linux"}
+    new = {"linux": "linux"}
+    it_r, en_r = TaxonomyView._detect_renames(old, new)
+    assert it_r == {}
+    assert en_r == {}
+
+
+def test_detect_renames_addition_not_rename(qtbot):
+    old = {"linux": "linux"}
+    new = {"linux": "linux", "vita": "life"}
+    it_r, en_r = TaxonomyView._detect_renames(old, new)
+    assert it_r == {}
+    assert en_r == {}