fix: resolve beta blockers in downloads, RPC, NAT, and proxy

[agalwood]

Summary

Resolve eight beta blockers affecting HTTP download naming and file display, aria2 RPC lifecycle, the downloads empty state, proxy-backed downloads and tracker sync, Windows NAT routing, and Windows torrent file associations.

This also updates Motrix to the published @motrix/nat@0.1.1 release from motrixapp/nat#1.

Issues

• Fixes [Bug]: 下载文件的文件名和后缀错误 #1976
• Fixes [Bug]: Tracker sync fails immediately when proxy is enabled #1977
• Fixes [Bug]: Rapidly clicking Restart Now after changing Performance Profile triggers multiple engine restarts and communication error #1987
• Fixes [Bug]: RPC 密钥留空导致 aria2 引擎无法启动（errorCode=28） #1988
• Fixes [Bug]: Glass Motion effect and floating menu permanently disappear after a task deletion error #1997
• Fixes [Bug]: Tailscale 导致 Windows 端 NAT 端口映射失败 #1999
• Fixes [Bug]: HTTP task file list displays .motrix temporary extension in action bar #2001
• Fixes [Bug]: Torrent file association icon displays main app icon instead of dedicated file icon on Windows #2003

Key changes

• Resolve HTTP filenames from the final request URI and response metadata after mux fallback and plugin hook rewrites.
  • Preserve an explicitly supplied filename.
  • Use bounded HEAD / ranged GET probes with redirect handling.
  • Honor request headers and explicit or global download proxy settings without leaking sensitive headers across origins.
  • Prefer Content-Disposition, then the redirected URL, and supplement missing extensions from Content-Type.
  • Sanitize untrusted remote filenames and retain safe URL-based fallbacks when probing fails.
• Keep the HTTP/FTP Files tab on the logical final filename instead of exposing aria2's .motrix staging suffix.
  • Preserve the engine and database physical paths while a download is active.
  • Rebase persisted file rows after the final rename, including plugin-overridden destinations.
  • Preserve legitimate .motrix payload names and leave BT, Magnet, and Mux paths untouched.
• Support an explicitly empty RPC secret as intentional no-token mode.
  • Missing or invalid persisted secrets still receive a generated secure default.
  • An explicit "" is preserved across saves and migrations.
  • No-token mode omits --rpc-secret and JSON-RPC token injection while keeping aria2 bound to loopback and disabling permissive cross-origin RPC access.
  • Refresh the RPC client credential before the first call to every newly started engine.
• Coalesce concurrent engine restart requests into one stop/start cycle and disable repeated “Restart Now” actions while a restart is pending.
• Restore the Glass Motion empty state when only removed task records remain by using the visible active-task count instead of the raw task mirror length.
• Make SOCKS5 usable for aria2 HTTP(S)/FTP downloads and tracker-list refreshes through an authenticated loopback HTTP bridge.
  • Generate fresh in-memory credentials for each listener, bind only to 127.0.0.1 on an ephemeral port, serialize lifecycle changes, and revoke credentials before shutdown.
  • Redact the authenticated proxy URL from aria2 process logs.
  • Clarify that BT peer, DHT, and UDP tracker traffic remains direct; the proxy covers BT HTTP(S) traffic only.
• Upgrade to @motrix/nat@0.1.1, which fixes Windows default-route selection in multi-adapter environments such as Tailscale and synchronizes the verified route before NAT mapping.
• Restore the dedicated .torrent file icon for Windows installer associations without reverting the installer-owned Default Apps design.
  • Install torrent.ico to a stable resources path before registering the Torrent ProgID.
  • Keep the application, Magnet, and Motrix protocol icons on the main executable and preserve Windows UserChoice safety.
  • Keep normal and restricted-signing builds aligned, including the reviewed verifier digests.

Validation

• Full Motrix test suite: 7,418 tests passed, 3 skipped.
• Windows NSIS installer compilation with the dedicated torrent icon: passed.
• TypeScript (tsc --noEmit): passed.
• Biome checks across 1,617 files: passed.
• Dependency-boundary and i18n checks: passed.
• Flatpak generated-source and third-party declaration checks: passed.
• @motrix/nat@0.1.1: 404 tests passed, 4 skipped; TypeScript, Biome, NAT lint, and package build passed.