feat(canvas): raise switch port cap to 64, add port numbers and fibre edge type

Issue #20: bump MAX_BOTTOM_HANDLES 48 -> 64 (covers 48+4 SFP switches) and add
a per-node "Show Port Numbers" toggle that labels each bottom connection point.

Issue #21: add `fibre` as a first-class edge/connection type (bright cyan with a
subtle glow) alongside ethernet/wifi/iot/vlan/virtual/cluster - selectable in the
edge modal, themeable, registered in the React Flow edgeTypes registry, and
round-tripped through YAML import/export.

Backport of homelable-hacs PR #23.

ha-relevant: yes

frontend/src/components/canvas/edges/index.tsx

@@ -323,6 +323,7 @@ export function HomelableEdge({ id, source, target, sourceHandleId, targetHandle
     vlan:     { strokeWidth: 2.5 },
     virtual:  { stroke: edgeColors.virtual,  strokeWidth: 1,   strokeDasharray: '4 4' },
     cluster:  { stroke: edgeColors.cluster,  strokeWidth: 2.5, strokeDasharray: '8 3' },
+    fibre:    { stroke: edgeColors.fibre,    strokeWidth: 2.5, filter: `drop-shadow(0 0 3px ${edgeColors.fibre}aa)` },
   }
 
   const customColor = data?.custom_color as string | undefined