remove backend dependency from iOS demo reveal

mobile/ios-app/Features/Round/RoundView.swift

@@ -329,7 +329,20 @@ struct RoundView: View {
             return
         }
 
-        guard let selectedOutcomeID, let session = repository.currentSession else {
+        guard let selectedOutcomeID else {
+            actionMessage = localization.string(for: "errors.session_expired")
+            return
+        }
+
+        if isDemoMode {
+            analytics.track("selection_submitted", attributes: baseSelectionAttributes(selectedOutcomeID))
+            analytics.track("selection_accepted", attributes: baseSelectionAttributes(selectedOutcomeID))
+            analytics.track("market_locked", attributes: baseSelectionAttributes(selectedOutcomeID).merging(["lock_reason": "swipe_selection"]) { _, new in new })
+            beginRevealTransition(for: round, selectedOutcomeID: selectedOutcomeID)
+            return
+        }
+
+        guard let session = repository.currentSession else {
             actionMessage = localization.string(for: "errors.session_expired")
             return
         }
@@ -371,7 +384,17 @@ struct RoundView: View {
                 analytics.track("selection_submitted", attributes: baseSelectionAttributes(selectedOutcomeID))
                 analytics.track("selection_accepted", attributes: baseSelectionAttributes(selectedOutcomeID))
                 analytics.track("market_locked", attributes: baseSelectionAttributes(selectedOutcomeID).merging(["lock_reason": "swipe_selection"]) { _, new in new })
+                beginRevealTransition(for: round, selectedOutcomeID: selectedOutcomeID)
+            } catch {
+                actionMessage = hermesUserFacingErrorMessage(localization: localization, localeCode: localization.localeCode, error: error) ?? localization.string(for: "errors.generic")
+                phase = .preview
+            }
 
+            isSubmitting = false
+        }
+    }
+
+    private func beginRevealTransition(for round: HermesRound, selectedOutcomeID: String) {
         phase = .locked
         playerCoordinator.play(rate: 2.0)
 
@@ -386,13 +409,6 @@ struct RoundView: View {
             playerCoordinator.play(url: revealMediaURL(for: round), startTimeMs: revealStartTimeMs(for: round), rate: 1.0)
             analytics.track("reveal_started", attributes: roundAnalyticsAttributes(round).merging(baseSelectionAttributes(selectedOutcomeID)) { _, new in new })
         }
-            } catch {
-                actionMessage = hermesUserFacingErrorMessage(localization: localization, localeCode: localization.localeCode, error: error) ?? localization.string(for: "errors.generic")
-                phase = .preview
-            }
-
-            isSubmitting = false
-        }
     }
 
     private func showResult() {
@@ -431,6 +447,10 @@ struct RoundView: View {
         repository.currentSession?.deviceModel == "Demo Device" ? MockHermesData.revealMediaURL() : round.media.hlsMasterUrl
     }
 
+    private var isDemoMode: Bool {
+        repository.currentSession?.deviceModel == "Demo Device"
+    }
+
     private func revealStartTimeMs(for round: HermesRound) -> Int {
         repository.currentSession?.deviceModel == "Demo Device" ? 0 : round.media.revealStartMs
     }