migration fixes

[Shackless]

Fixes several problems reported by a tester who updated from Wingman AI 2.1.1 to 3.1.6:

• Updating from an old version could wipe your settings. When the update had to
  jump across several versions at once, changes got lost along the way and Wingman AI
  silently fell back to factory settings — audio devices, voice activation, STT
  configuration, everything. Updates now carry all your settings over correctly, no
  matter how old the version you're coming from is.
• A single missing custom skill blocked a whole config. If one of your Wingmen
  used a custom skill that isn't installed on your PC (anymore), the entire config
  refused to load. Now the missing skill is simply skipped with a warning and
  everything else keeps working. Your settings for that skill are kept, so it comes
  back as soon as you reinstall it.
• Saving settings could fail with an error while Wingman AI was still starting up
  or when no config was loaded.

Also fixed in the Client (ships with the same release): the on/off switches for
whispercpp, XVASynth and persistent memory looked enabled but were never actually
saved — which is why whispercpp kept turning itself off even after a successful
connection test.

If this bug already reset your settings: update, close Wingman AI, delete everything > 2.1.1 in %APPDATA%\ShipBit\WingmanAI, and start again — the update will
re-run and restore everything from your old version.