Use RoundedBorder for all sample Table widgets (Spectre.Console 0.57.0)

[Copilot]

Spectre.Console 0.57.0 added new box border styles (rounded, dashed, dotted, heavy, beveled). The sample apps were using either the default border or MinimalBorder() with no visual polish.

Changes

• MostVersatileMaterials/ItemCard.cs — added .RoundedBorder() (was default)
• MostVersatileMaterials/RecipesTable.cs — added .RoundedBorder() (was default)
• ApiVersionInfo/RouteTable.cs — replaced .MinimalBorder() with .RoundedBorder()
• ApiVersionInfo/ReleaseNoteTable.cs — replaced .MinimalBorder() with .RoundedBorder()

RoundedBorder was chosen for all four tables to keep visual style consistent across samples. The rounded ╭─╮ corners complement the emoji-rich table content without adding visual noise.

// Before
private readonly Table table = new Table()
    .AddColumn("Route")
    .AddColumn("Authorization")
    .AddColumn("Localization")
    .MinimalBorder();

// After
private readonly Table table = new Table()
    .AddColumn("Route")
    .AddColumn("Authorization")
    .AddColumn("Localization")
    .RoundedBorder();