fix: share payment targets dialog with reactions row, restore QR glyph

- Extract PaymentTargetsDialog from PaymentButton so the reactions row
  can render the same QR/Copy/Pay layout instead of the legacy two-row
  M3ActionRow per target.
- PayReaction now subscribes via EventFinderFilterAssemblerSubscription
  and observes the PaymentTargetsEvent reactively, so targets actually
  load when the wallet icon is tapped.
- Correct the QrCode2 codepoint (U+E00A) and re-subset the bundled
  Material Symbols Outlined font so the glyph is no longer a tofu box.

https://claude.ai/code/session_01JtJuvSYMusKiDMWo7N8Aj8

commons/src/commonMain/kotlin/com/vitorpamplona/amethyst/commons/icons/symbols/MaterialSymbols.kt

@@ -175,7 +175,7 @@ object MaterialSymbols {
     val Public = MaterialSymbol("\uE80B")
     val PublicOff = MaterialSymbol("\uF1CA")
     val PushPin = MaterialSymbol("\uF10D")
-    val QrCode2 = MaterialSymbol("\uEF6B")
+    val QrCode2 = MaterialSymbol("\uE00A")
     val RadioButtonChecked = MaterialSymbol("\uE837")
     val RadioButtonUnchecked = MaterialSymbol("\uE836")
     val Recommend = MaterialSymbol("\uE9D2")