Add Windows portable release support

[jabrailkhalil]

What changed

• Adds the Windows portable electron-builder target alongside the existing NSIS installer.
• Adds portable-mode path setup using PORTABLE_EXECUTABLE_DIR from electron-builder, with VIDBEE_PORTABLE_DIR as a local/testing override.
• Keeps portable app data, session data, logs, crash dumps, temp data, Deno cache, and default downloads under the portable executable directory.
• Disables auto-update behavior and launch-at-login persistence in portable mode.
• Skips default protocol handler registration in portable mode to avoid registry writes.

Why

This implements the direction proposed in #401: a no-install Windows release artifact for USB / isolated / portable use cases while preserving the existing installer behavior for normal Windows users.

The regular installer path remains unchanged because portable mode only activates when PORTABLE_EXECUTABLE_DIR or VIDBEE_PORTABLE_DIR is present.

Validation

• corepack pnpm --filter ./apps/desktop run check
• corepack pnpm --filter ./apps/desktop run build
• corepack pnpm --filter ./apps/desktop exec electron-builder --win portable --publish never

The portable packaging command produced:

apps/desktop/dist/vidbee-1.3.10-portable.exe

Local Windows Sandbox testing from #401 also verified that the manually wrapped portable launch kept config/download paths inside the portable folder and left 0 matches in the checked host trace locations after Sandbox shutdown.

[jabrailkhalil]

Follow-up validation for commit 2f88402:

• Hid the main window until both Electron ready-to-show and a renderer-side app:renderer-ready signal are received, so the packaged app no longer exposes Electron's blank pre-render frame before the themed UI is mounted.
• Extended portable mode to create standard home folders (Desktop, Documents, Downloads, Music, Pictures, Videos) and set Electron app paths for them. This fixes Windows native file dialogs falling back to a missing portable Desktop path.
• Made fs.getDefaultDownloadPath() return the portable Downloads folder in portable mode, matching settings/default download behavior.

Checks run on Windows:

• pnpm --filter ./apps/desktop run check
• pnpm --filter ./apps/desktop run build
• pnpm --filter ./apps/desktop exec electron-builder --win portable --publish never
• Smoke-tested packaged win-unpacked through renderer IPC: app info, settings locks, portable download paths, cookies file validation, browser profile path validation, download queue status, history/subscriptions reads, update-disabled behavior, thumbnail/window IPC.
• Opened and closed the native fs.selectFile dialog from IPC; no Location is not available dialog appeared and the dialog resolved cleanly with null when canceled.

[jabrailkhalil]

Follow-up for release coverage in commit c75d1e9:

• Added a Windows release artifact check in the reusable build workflow so CI explicitly requires both *-setup.exe and *-portable.exe after the Windows build.
• Set if-no-files-found: error on the artifact upload step so release uploads fail loudly if no build artifacts are present.

Local validation:

• pnpm --filter ./apps/desktop run check
• pnpm --filter ./apps/desktop exec electron-builder --win --publish never
• Verified the same PowerShell check finds both vidbee-1.3.10-setup.exe and vidbee-1.3.10-portable.exe in apps/desktop/dist.

[jabrailkhalil]

Follow-up for the user-facing portable folder release in commit 9ad0b16:

This adds a second Windows portable distribution format in addition to electron-builder's *-portable.exe:

• vidbee-<version>-windows-portable.zip
• The ZIP contains a VidBee-portable/ folder with:
  • app/ copied from dist/win-unpacked
  • VidBee Portable.lnk
  • hidden-window launchers: Start-VidBee-Portable.vbs and Start-VidBee-Portable.ps1
  • pre-created Data/, Downloads/, and Temp/ folders
  • README-portable.txt

The folder launcher sets VIDBEE_PORTABLE_DIR, redirects app/profile/cache/temp paths into the extracted folder, and starts the packaged app with a local --user-data-dir. This gives users the familiar "download zip, extract folder, run shortcut" portable workflow.

Release coverage:

• build:win now creates the folder ZIP after electron-builder --win.
• The reusable build workflow now requires *-setup.exe, *-portable.exe, and *-windows-portable.zip.
• release.yml already uploads dist/*.zip, so the folder archive will be attached to GitHub Releases.

Local validation:

• Ran scripts/create-windows-portable-folder.ps1 successfully.
• Verified ZIP contents include the shortcut, launchers, app/vidbee.exe, and app/resources/app.asar.
• Extracted the ZIP into a fresh directory and launched VidBee Portable.lnk; it started app/vidbee.exe from the extracted folder.
• pnpm --filter ./apps/desktop run check passed.