feat(config): ProxyJump visualization, drag reorder, order hint

[luizomf]

Summary

• ProxyJump chain visualization: when a host has ProxyJump set, an inline diagram shows the hop path (Você → bastion → db-server). Multi-hop chains are resolved by following ProxyJump references through other defined hosts. Circular refs are handled.
• Drag-and-drop reorder: host cards are draggable. Output reflects the visual order. A hint note appears when 2+ hosts are present: "A ordem importa — o SSH usa o primeiro Host que combinar."
• Drag handle: ☰ icon on each card header for discoverability.
• Wildcards already work in the Host field — the generator handles them natively.
• All 114 tests pass.

Closes #7

Test plan

• Add bastion + db-server with ProxyJump → chain diagram shows "Você → bastion → db-server"
• Change ProxyJump value → chain updates live
• Remove ProxyJump → chain hides
• Multi-hop: A → B → C shows full chain
• Drag a card to reorder → output updates with new order
• Order hint shows when 2+ hosts, hides when 0-1
• Use-case "bastion host" card → chain appears on db-server
• Wildcard host (e.g., "*.prod") accepted in Host field

🤖 Generated with Claude Code