refactor(stage-3): add Keep-Alive connection pool for Ollama, implement offline lemma resolution in dictionary

app/dictionary.py

@@ -303,9 +303,29 @@ async def lookup_term(query: str) -> Dict[str, Any]:
                     "SELECT term, translation, phonetic, pos FROM offline_dictionary WHERE term = ? COLLATE NOCASE",
                     (query_clean,)
                 ).fetchone()
+
+                lemma_found = None
+                if not off_row and len(words) == 1:
+                    try:
+                        from app.phrasal import lemmatize_word
+                        for cand in lemmatize_word(query_clean):
+                            if cand.lower() != query_clean.lower():
+                                row = conn.execute(
+                                    "SELECT term, translation, phonetic, pos FROM offline_dictionary WHERE term = ? COLLATE NOCASE",
+                                    (cand,)
+                                ).fetchone()
+                                if row:
+                                    off_row = row
+                                    lemma_found = row["term"]
+                                    break
+                    except Exception:
+                        pass
+
                 if off_row:
                     raw_trans = off_row["translation"] or ""
                     clean_trans = clean_russian_translation(raw_trans)
+                    if lemma_found and lemma_found.lower() != query_clean.lower():
+                        clean_trans = f"{clean_trans} (от {lemma_found})"
                     tr_list = [t.strip() for t in clean_trans.split(",") if t.strip()]
                     res = {
                         "query": query_clean,