feat(upgrade): Merge upgrade screen mascot and preamble into one hero card

Adds UpgradeHeroCard, which pairs the mascot with the preamble copy inside a
single ElevatedCard and stacks them once the copy runs out of room. Used by
the FOSS pitch view and the GPLAY acquisition view; grace episodes and the
FOSS status views keep their standalone header, which has no preamble to
pair with. Screen tests pin the hero's presence and absence per state.

app/src/gplay/java/eu/darken/capod/common/upgrade/ui/UpgradeScreen.kt

@@ -244,10 +244,23 @@ internal fun UpgradeScreen(
                 // episode ages into the diagnostics stage, the mascot joins the mood: unimpressed
                 // at Google Play, matching the setup card's "needs your attention" face. The young
                 // episode keeps the happy face — its message is that nothing is wrong.
-                UpgradeHeader(
-                    mascotSize = 88.dp,
-                    happy = loaded?.grace?.showDiagnostics != true,
-                )
+                if (loaded?.grace != null) {
+                    // Grace users never see the preamble (sales copy contradicts "still active"),
+                    // so there is nothing to pair the mascot with — it stays a standalone header
+                    // above the grace card.
+                    UpgradeHeader(
+                        mascotSize = 88.dp,
+                        happy = loaded.grace.showDiagnostics != true,
+                    )
+                } else {
+                    UpgradeHeroCard(
+                        text = stringResource(R.string.upgrade_preamble),
+                        colors = CardDefaults.elevatedCardColors(
+                            containerColor = MaterialTheme.colorScheme.secondaryContainer,
+                            contentColor = MaterialTheme.colorScheme.onSecondaryContainer,
+                        ),
+                    )
+                }
             }
 
             if (ownedState != null) {
@@ -296,14 +309,8 @@ private fun UpgradeAcquisitionContent(
     // blip) shows calm status only, an aged one (likely really gone) adds restore AND the offers,
     // so an expired subscriber can switch without waiting out the full grace window.
     if (!inGrace) {
-        UpgradePreambleCard(
-            text = stringResource(R.string.upgrade_preamble),
-            colors = CardDefaults.elevatedCardColors(
-                containerColor = MaterialTheme.colorScheme.secondaryContainer,
-                contentColor = MaterialTheme.colorScheme.onSecondaryContainer,
-            ),
-        )
-
+        // The preamble itself now lives in the hero card at the top of the screen, next to the
+        // mascot — only the sections below it are conditional here.
         if (uiState is GplayUpgradeUiState.Loaded && uiState.wasPreviouslyPro) {
             // The targeted returning-buyer nudge: prominent placement and emphasis, and the ONLY
             // restore affordance on the screen — a second one below would make the screen feel