Setup UX: allow Start w/ unsaved changes; hide delete for built-ins

app/src/main/java/com/mindmachine/mvp/session/MainViewModel.kt

@@ -34,6 +34,9 @@ data class UiState(
     val selectedPreset: SessionPreset = Presets.builtIn.first(),
     val config: SessionConfig = Presets.builtIn.first().toConfig(),
 
+    // Only user-saved programs (including customizations of built-ins) are deletable.
+    val deletableProgramIds: Set<String> = emptySet(),
+
     // Timeline program (curves) used for both editing + runtime modulation.
     val timeline: TimelineEditorState = TimelineProgramFactory.fromPreset(Presets.builtIn.first()),
     val savedProgramName: String = Presets.builtIn.first().name,
@@ -101,6 +104,7 @@ class MainViewModel(
             combine(settingsRepository.settings, userProgramRepository.userPrograms) { settings, userPrograms ->
                 settings to userPrograms
             }.collect { (settings, userPrograms) ->
+                val userProgramIds = userPrograms.map { it.id }.toSet()
                 val builtInPrograms = Presets.builtIn.map { preset ->
                     userPrograms.firstOrNull { it.id == preset.id } ?: UserProgramEntity(
                         id = preset.id,
@@ -121,7 +125,9 @@ class MainViewModel(
                         description = it.description,
                         timeline = it.timeline,
                         sortOrder = it.sortOrder,
-                        isUserProgram = true,
+                        // Deletable only when the user explicitly saved it (either custom program,
+                        // or a customized built-in stored in the user program store).
+                        isUserProgram = it.id in userProgramIds,
                     )
                 }
 
@@ -142,6 +148,7 @@ class MainViewModel(
                         savedProgramName = savedName,
                         savedTimelineSignature = savedSignature,
                         hasUnsavedChanges = isDirty(selectedPreset.name, nextTimeline, savedName, savedSignature),
+                        deletableProgramIds = userProgramIds,
                     )
                 }
             }