Add saved Netgraph region arrangement and traffic filters

docs/netgraph.md

@@ -7,3 +7,18 @@ Nodes are grouped by four-character Maidenhead grid squares, each two degrees of
 Live packets retain their hop order, protocol colours and synchronized sound. Matching packets receive bounded emphasis while a node is inspected. Area cues show LOCAL traffic or paired OUT/IN activity; DX identifies qualifying long-distance inter-area traffic. Other traffic remains visible and every visible hop keeps its musical note.
 
 Use mouse/wheel, native touch gestures, or the zoom buttons. Reset fits the whole topology, including networks spanning continents. Finder supports Up/Down, Enter and Escape. On slower renderers, secondary decoration and compositing adapt to measured frame cost without dropping live hops or hiding topology. Reduced motion retains stable cues and fading residue.
+
+### Arrange and filter regions
+
+In Netgraph, open **Display → Region layout** to spread region centres from 100% to
+400%. Drag a region label to move its whole bubble, or choose a region and use
+the arrow buttons. **Reset region layout** restores the geographic arrangement.
+Nodes keep their positions inside each bubble; routes and live packets follow
+when the bubble moves. These controls change the diagram, not reported locations.
+
+Use **Regions** to search IATA/region codes or names and select multiple regions.
+**None** followed by one checkbox isolates a region; **All** restores the full mesh.
+Only connections with both endpoints in the selected regions are shown. Search
+and Follow respect this selection. Use **Routes** to hide standing connections;
+live packets still illuminate their paths and leave a brief fading trace.
+Layout, region choices and route visibility are remembered in this browser.