refactor: comentarii strict functionale, fara referinte PRD/stories

Curatare globala a comentariilor si docstring-urilor (app, tools, teste,
scripturi): eliminate referintele la PRD-uri, US-xxx, task-uri istorice si
review-uri; pastrata doar informatia functionala, formulata scurt. Regula
adaugata in CLAUDE.md (sectiunea Stil). Fara modificari de cod sau comportament.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_users.py

@@ -1,4 +1,4 @@
-"""Teste US-001 (PRD 3.3): tabela users + helper-e parole scrypt in app/users.py."""
+"""Tabela users + helper-e parole scrypt in app/users.py."""
 
 from __future__ import annotations
 
@@ -83,7 +83,7 @@ def test_get_user_by_email(conn, account_id):
 
 
 def test_parola_scurta_si_lunga_eroare(conn, account_id):
-    """Parola < 10 caractere sau > 128 ridica ValueError (C9 anti-DoS)."""
+    """Parola < 10 caractere sau > 128 ridica ValueError (anti-DoS)."""
     from app.users import create_user
     with pytest.raises(ValueError):
         create_user(conn, account_id, "scurta@ex.ro", "scurt")