fix(theme): inset-aware chrome compaction (no first-frame snap)

Previous attempt computed total chrome height as
`Modifier.height(content + insetReadViaPaddingValues)`. The inset is
read at composition time and arrives as 0 on the very first frame
before the system-bar inset connection delivers its value — the bar
laid out at the shorter (no-inset) height, then re-measured once the
inset arrived. Visible as a one-frame snap on app cold start.

Switch to a layout-time pattern that subscribes to inset changes
correctly:

    Modifier
        .windowInsetsPadding(insets)   // reserves the inset via padding
        .height(contentHeight)         // content area only

`windowInsetsPadding` is a Modifier.Node that re-layouts (not re-
composes) on inset arrival, so the bar measures at the right total
height on the first frame. The bar's own `windowInsets` is set to
`WindowInsets(0)` so it doesn't double-pad.

Applied to:
- `BottomBar` NavigationBar — content height 56dp + navigation-bars inset
- `FeedScreen` CenterAlignedTopAppBar — content height 48dp + status-bars
  inset

app/src/main/kotlin/com/wisp/app/ui/component/BottomBar.kt

@@ -19,8 +19,9 @@ import androidx.compose.material.icons.outlined.Search
 import androidx.compose.material3.Icon
 import androidx.compose.ui.res.painterResource
 import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.asPaddingValues
+import androidx.compose.foundation.layout.WindowInsets
 import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.windowInsetsPadding
 import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.NavigationBar
@@ -81,14 +82,16 @@ fun WispBottomBar(
             // + chrome and reserves the lighter "surface" for elevated
             // controls (pills, cards).
             containerColor = MaterialTheme.colorScheme.background,
-            // Material's default 80dp NavigationBar reserves a tall slot
-            // for labels we never render — clamp to 56dp + the gesture
-            // inset for a chrome height closer to the iOS tab bar.
-            modifier = Modifier.height(
-                56.dp + NavigationBarDefaults.windowInsets
-                    .asPaddingValues().calculateBottomPadding()
-            ),
-            windowInsets = NavigationBarDefaults.windowInsets
+            // Compact the chrome: reserve the gesture inset via
+            // `windowInsetsPadding` (resolved at layout time, so no
+            // first-frame snap) and clamp the content area to 56dp
+            // (was Material's default 80dp). Pass `WindowInsets(0)` to
+            // disable NavigationBar's internal inset handling so we
+            // don't double-pad.
+            modifier = Modifier
+                .windowInsetsPadding(NavigationBarDefaults.windowInsets)
+                .height(56.dp),
+            windowInsets = WindowInsets(0)
         ) {
         visibleTabs.forEach { tab ->
             val selected = currentRoute == tab.route

app/src/main/kotlin/com/wisp/app/ui/screen/FeedScreen.kt

@@ -15,8 +15,8 @@ import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.WindowInsets
-import androidx.compose.foundation.layout.asPaddingValues
 import androidx.compose.foundation.layout.statusBars
+import androidx.compose.foundation.layout.windowInsetsPadding
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
@@ -752,14 +752,15 @@ fun FeedScreen(
             contentWindowInsets = WindowInsets(0, 0, 0, 0),
             topBar = {
                 CenterAlignedTopAppBar(
-                    // Material's default 64dp content + status-bar inset
-                    // pads a chunky gap below the icon row. Clamp to 48dp
-                    // + status-bar inset so the chrome lands closer to
-                    // the iOS navigation bar (~44dp content + safe-area).
-                    modifier = Modifier.height(
-                        48.dp + WindowInsets.statusBars
-                            .asPaddingValues().calculateTopPadding()
-                    ),
+                    // Compact: reserve the status-bar inset via
+                    // `windowInsetsPadding` (layout-time, no first-frame
+                    // snap) and clamp the content area to 48dp (was
+                    // Material's default 64dp). Disable the bar's
+                    // internal inset handling to avoid double-padding.
+                    modifier = Modifier
+                        .windowInsetsPadding(WindowInsets.statusBars)
+                        .height(48.dp),
+                    windowInsets = WindowInsets(0),
                     title = {
                                 Box {
                                     Surface(