feat(5.18): VERIFY+CLOSE — US-007 badge sursa + fix findings code-review

VERIFY PASS pe corpus k-NN exemple etichetate (seed real 17181 Haiku, comis
in 756f777): suita 1392 passed, 1 deselected (live); smoke init_db seeder
(17181/NUL=2200/idempotent); toate codurile in nomenclator.

US-007 (cerere user la CLOSE) — badge sursa pe sugestia fuzzy din editor:
- _mapari.html: chip confirmat (GOLD) / similar (SILVER+k-NN) / non-operatie (NUL)
- base.html: .sugg-sursa--{confirmat,similar,nul} pe tokeni de tema (color-mix)
- routes.py: cheia `nul` adaugata in surse_sugestie default (finding cross-file)
- tests/test_web_badge_sursa.py: gold/silver/nul/fara-sursa (4 teste)
- E2E render live verificat in serverul real (/_fragments/mapari)

CLOSE /code-review high (main..HEAD, 3 finder x 8 unghiuri) — runtime curat,
invariant #13 intact; 3 findings low/cosmetic REPARATE + lock-uite:
- shared_store.seed_suggestions: cod whitespace -> NULL (era ''), + test lock
- genereaza_seed.py: with open(...) in loc de open().read() (FD leak tool offline)
- embeddings.py: docstring-uri aliniate la [{cod, is_nul, similaritate}]

ROADMAP: 5.18 LIVRAT. PRD: raport VERIFY/CLOSE scris.

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

tools/mapare-llm/genereaza_seed.py

@@ -113,7 +113,8 @@ def _incarca_seed(seed_path: str | None) -> list[dict]:
     if not seed_path or not os.path.exists(seed_path):
         return []
     try:
-        return json.loads(open(seed_path, encoding="utf-8").read())
+        with open(seed_path, encoding="utf-8") as fh:
+            return json.loads(fh.read())
     except (ValueError, OSError):
         return []
 
@@ -132,7 +133,8 @@ def construieste_harta_etichete(
 
     # labels-groq-partial.json: cheiat pe text BRUT.
     if labels_path and os.path.exists(labels_path):
-        labels = json.loads(open(labels_path, encoding="utf-8").read())
+        with open(labels_path, encoding="utf-8") as fh:
+            labels = json.loads(fh.read())
         for raw, cod in labels.items():
             cheie = normalize_for_match(raw)
             if not cheie: