fix(roaming): stretch side cells to 80dp like the reference RelativeLayout

The user spotted two white "beams" (20dp gaps) between the center
cell and the side cells. Root cause: the reference app's RelativeLayout
ignores the fixed 60dp width when a child has BOTH a left rule
(alignParentLeft) and a right rule (toLeftOf=center cell) - the width
is stretched to right-rule minus left-rule, i.e. 80dp on a 360dp
screen. The three cells therefore sit flush with only 2dp margins
between them, no gaps.

Port that behavior: side cells 60dp -> 80dp (6 places), center cell
stays 200dp centered. Verified against the reference screenshot pixel
measurements (side cells ~76.5dp incl. margins, center ~198dp).

Verified: feature + app compile, 11 unit tests pass. Marker lookup,
grid math and GPS logic untouched.

feature/roaming/src/main/java/com/rtbishop/look4sat/feature/roaming/RoamingScreen.kt

@@ -269,13 +269,13 @@ fun RoamingScreen() {
         Column(modifier = Modifier.fillMaxWidth().weight(1f).padding(bottom = 15.dp)) {
             // 行1: relativeLayout5 (上排: 纬度 +1)
             Box(modifier = Modifier.fillMaxWidth().weight(1f)) {
-                GridCell(text = state.grids[0], modifier = Modifier.width(60.dp).fillMaxHeight().align(Alignment.CenterStart))
+                GridCell(text = state.grids[0], modifier = Modifier.width(80.dp).fillMaxHeight().align(Alignment.CenterStart))
                 GridCell(text = state.grids[1], modifier = Modifier.width(200.dp).fillMaxHeight().align(Alignment.Center))
-                GridCell(text = state.grids[2], modifier = Modifier.width(60.dp).fillMaxHeight().align(Alignment.CenterEnd))
+                GridCell(text = state.grids[2], modifier = Modifier.width(80.dp).fillMaxHeight().align(Alignment.CenterEnd))
             }
             // 行2: relativeLayout4, 205dp 高 (中排: 中央)
             Box(modifier = Modifier.fillMaxWidth().height(205.dp)) {
-                GridCell(text = state.grids[3], modifier = Modifier.width(60.dp).fillMaxHeight().align(Alignment.CenterStart))
+                GridCell(text = state.grids[3], modifier = Modifier.width(80.dp).fillMaxHeight().align(Alignment.CenterStart))
                 // 中央列: tv22 (100x80dp centerInParent) 叠在 linearLayout3 (200x200dp) 之上
                 Box(modifier = Modifier.width(200.dp).fillMaxHeight().align(Alignment.Center)) {
                     // linearLayout3: 200x200dp, marginTop 2dp, holo_blue_bright
@@ -307,13 +307,13 @@ fun RoamingScreen() {
                             .align(Alignment.Center)
                     )
                 }
-                GridCell(text = state.grids[5], modifier = Modifier.width(60.dp).fillMaxHeight().align(Alignment.CenterEnd))
+                GridCell(text = state.grids[5], modifier = Modifier.width(80.dp).fillMaxHeight().align(Alignment.CenterEnd))
             }
             // 行3: relativeLayout3 (下排: 纬度 -1)
             Box(modifier = Modifier.fillMaxWidth().weight(1f)) {
-                GridCell(text = state.grids[6], modifier = Modifier.width(60.dp).fillMaxHeight().align(Alignment.CenterStart))
+                GridCell(text = state.grids[6], modifier = Modifier.width(80.dp).fillMaxHeight().align(Alignment.CenterStart))
                 GridCell(text = state.grids[7], modifier = Modifier.width(200.dp).fillMaxHeight().align(Alignment.Center))
-                GridCell(text = state.grids[8], modifier = Modifier.width(60.dp).fillMaxHeight().align(Alignment.CenterEnd))
+                GridCell(text = state.grids[8], modifier = Modifier.width(80.dp).fillMaxHeight().align(Alignment.CenterEnd))
             }
         }
         // tv4: 底部版权, 10sp 黑 (往上拉, 底部预留空间避免被导航栏遮挡)