Skip malformed personal keyword index rows

Make personal keyword retrieval tolerate corrupted non-dict index entries and missing chunk lists, with regression coverage.

tests/test_personal_docs_keyword_nondict.py

@@ -0,0 +1,21 @@
+from src.personal_docs import retrieve_personal_keyword
+
+
+def test_retrieve_personal_keyword_skips_non_dict_rows():
+    # A corrupted personal index can hold non-dict rows (partial write, bad
+    # import). The old loop did f["chunks"] which raised TypeError on a str
+    # row and aborted the whole search; now bad rows are skipped.
+    index = [
+        "bad-row",
+        None,
+        ["also", "bad"],
+        {"name": "report.txt", "chunks": ["hello world from the quarterly report"]},
+    ]
+    out = retrieve_personal_keyword(index, "hello", k=5)
+    assert out == ["[report.txt :: chunk 1]\nhello world from the quarterly report"]
+
+
+def test_retrieve_personal_keyword_tolerates_missing_chunks_key():
+    index = [{"name": "empty.txt"}, {"name": "doc.txt", "chunks": ["alpha beta gamma"]}]
+    out = retrieve_personal_keyword(index, "beta", k=5)
+    assert out == ["[doc.txt :: chunk 1]\nalpha beta gamma"]