Summary

• Welcome window, connection form, and feedback panel reverted to a centered default every time they reopened, because their factories called window.center() and never set a frame autosave name. Only the main editor (MainEditorWindow) and the SwiftUI Settings scene remembered position.
• Added a small NSWindow.applyAutosaveName(_:) extension that wraps the native AppKit pattern (setFrameAutosaveName + setFrameUsingName with center() as first-launch fallback) and applied it to all four custom windows: Welcome, Connection Form (shared key for new + edit), Feedback panel, and Main Editor (refactored from inline setFrameAutosaveName for consistency).
• Settings window untouched: SwiftUI's Settings { } scene already handles position persistence.

Test plan

• Open the welcome window, drag it to a new position, quit the app, relaunch — welcome reopens at the saved position
• Open the connection form (new connection), move it, close it, reopen — same position
• Open an edit-connection form, move it, close, then open a different connection's edit form — opens at the saved position (shared autosave key by design)
• Report an Issue panel: move it, close, reopen — same position
• Main editor window position still persists across launches (regression check)
• Fresh install (delete app domain from defaults): all four windows open centered on first launch