v0.12.1: fix vv version display, HDD default path, backup status colors, button contrast

- Bug 1: Remove hardcoded 'v' prefix from templates (layout.html, settings.html); version tag already contains 'v'
- Bug 2: primaryHDDPath() and metrics collector now use GetDefaultStoragePath() instead of paths[0].Path so the real HDD is used, not the first (SSD) path
- Bug 3: Apps without HDD data show green/yellow based on volumeLastStatus instead of always gray
- Bug 5: Add default background rgba(255,255,255,0.1) to .btn to fix white-on-transparent readability

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

controller/internal/web/handlers.go

@@ -654,9 +654,17 @@ func (s *Server) buildAppBackupRows(
 				}
 			}
 		} else {
-			// No HDD data — fully automatic
-			row.Status = "auto"
-			row.StatusText = "Automatikus mentés (nincs felhasználói adat)"
+			// No HDD data — everything backed up automatically via restic
+			if volumeLastStatus == "ok" {
+				row.Status = "green"
+				row.StatusText = "Mentés rendben"
+			} else if volumeLastStatus == "error" {
+				row.Status = "yellow"
+				row.StatusText = "Kötetek mentése sikertelen"
+			} else {
+				row.Status = "auto"
+				row.StatusText = "Automatikus mentés"
+			}
 		}
 
 		// If DB dump failed for this app, degrade to yellow (if not already red)