ui: restore a 50px top header with centered brand; rename to CoRE.Vizion+

Re-add the top header as a 50px bar injected by ensureHeader() on every
layout page (skipped on login), with the brand centered. The layout height
now subtracts both header and footer. Rebrand the project CoRE.Vision →
CoRE.Vizion+ everywhere: header + footer brand, all page <title>s, the login
card, and the FastAPI OpenAPI title (applies on next backend restart).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/app/main.py

@@ -70,7 +70,7 @@ async def lifespan(app: FastAPI):
         await runtime.db.close()
 
 
-app = FastAPI(title="CoRE.Vision", version="1.0", lifespan=lifespan)
+app = FastAPI(title="CoRE.Vizion+", version="1.0", lifespan=lifespan)
 
 # публичные пути (без авторизации)
 PUBLIC_PATHS = {"/login", "/api/login", "/api/health"}