Sportski objekti: API + Leaflet map page + address enrichment

DB: pgz_sport.sportski_objekti (103 objekti, 103 s geo, 60 s adresom, 31 tip)

API:
- /api/v2/sportski-objekti (filter: tip, grad, sport, q)
- /api/v2/sportski-objekti/meta (tipovi, gradovi, sportovi, ukupno)

Frontend:
- /static/objekti.html — Leaflet (OpenStreetMap) interactive map
- 3 dropdown filter (tip, grad, sport) + search
- Side panel s listom + map markers s ikonama (🏟️⚽🏊⛵🎿🎳⛸️🎯🥌🏃)
- Popup: naziv, tip, kapacitet, adresa, upravitelj, izgradeno, sportovi, web link, Google Maps link
- /objekti, /sport/objekti, /sport/api/v2/sportski-objekti routes

Sidebar app.html: +Sportski objekti link
Background: scripts/objekti_enrich_address.py (Nominatim reverse-geocode 60 objekata bez adrese)

static/app.html

@@ -506,6 +506,7 @@ const NAV_BY_ROLE = {
     {id:'dashboard',  ic:'\u{1F4CA}', label:'Dashboard'},
     {id:'korisnici',  ic:'\u{1F465}', label:'Korisnici', href:'/admin/users'},
     {id:'savezi',     ic:'\u{1F3C5}', label:'Savezi'},
+    {id:'objekti',    ic:'\u{1F3DF}', label:'Sportski objekti', href:'/objekti'},
     {id:'klubovi',    ic:'⬢',        label:'Klubovi'},
     {id:'sportasi',   ic:'\u{1F464}', label:'Sportaši'},
     {id:'financije',  ic:'€',         label:'Financije'},