Fix sprite.version crash and stale anim name on preset switch

- Remove app.sprite.version (doesn't exist in Aseprite API), use
  filename + frame number + periodic refresh every 2.5s for edits
- Clamp previewSingleIdx and update pvAnimName label when switching
  presets, so One mode doesn't show names from another preset

aniphallow.lua

@@ -1586,20 +1586,25 @@ openPreviewWindow = function()
     }
     previewTimer:start()
 
-    local pvStaLastVersion = 0  -- track sprite version to detect edits
+    local pvStaLastFile = ""
     local pvStaLastFrame = 0
+    local pvStaTickCount = 0
 
     pvRefreshTimer = Timer{
         interval = 0.5,
         ontick = function()
             refreshLockFile()
             if S.previewMode == "static" then
-                -- Only refresh source and repaint when sprite actually changed
-                local curVer = app.sprite and app.sprite.version or 0
+                -- Detect file or frame change cheaply
+                local curFile = app.sprite and app.sprite.filename or ""
                 local curFrame = app.frame and app.frame.frameNumber or 0
-                if curVer ~= pvStaLastVersion or curFrame ~= pvStaLastFrame then
-                    pvStaLastVersion = curVer
+                local changed = (curFile ~= pvStaLastFile or curFrame ~= pvStaLastFrame)
+                pvStaLastFile = curFile
                 pvStaLastFrame = curFrame
+                -- Also refresh every 5 ticks (2.5s) to catch edits
+                pvStaTickCount = pvStaTickCount + 1
+                if changed or pvStaTickCount >= 5 then
+                    pvStaTickCount = 0
                     refreshSource()
                     pcall(function() previewDlg:repaint() end)
                 end
@@ -1617,6 +1622,20 @@ openPreviewWindow = function()
                 if presetForFile ~= S.currentPreset then
                     loadPreset(presetForFile)
                     S.currentPreset = presetForFile
+                    -- Clamp previewSingleIdx to new preset's anims
+                    if #S.animNames == 0 then
+                        S.previewSingleIdx = 1
+                    elseif S.previewSingleIdx > #S.animNames then
+                        S.previewSingleIdx = #S.animNames
+                    end
+                    -- Update preview label for One mode
+                    pcall(function()
+                        local name = ""
+                        if S.previewSingleIdx >= 1 and S.previewSingleIdx <= #S.animNames then
+                            name = S.animNames[S.previewSingleIdx]
+                        end
+                        previewDlg:modify{ id = "pvAnimName", text = name }
+                    end)
                     -- Refresh UI if main dialog is open (don't touch preview - avoids repositioning)
                     if mainDlg then
                         pcall(function() mainDlg:close() end)