Preserve legacy source data when portable sanitization cannot replace it, reject malformed settings without panicking, and make portable pairing regeneration durable before UI state changes.\n\nMake the packaged smoke assertion tolerate slow WebView startup and clarify AppImage storage behavior.\n\nRefs #15
Implement marker-based portable storage, portable WebView and log paths, secure queue and migration sanitization, and Windows portable ZIP validation while preserving the NSIS installer path.
Refs #15