Bugfix/outfit visuals handling

[Blizzardsev]

Resolves the following:

• Issue where the headphones idle resulted in some inconsistent display of Natsuki's current outfit
• Issue where Natsuki's animation would play rapidly during weather changes, related to Ren'Py accelerating animations when playing Dissolve/Fade animations - Natsuki now switches to a static sprite during this phase. Some edge cases may pop up, but not much can be done about these.
• Removed beach assets for discontinued beach location
• Issue where dim assets would disappear instead of fading out smoothly (like clouds); dim assets have also been adjusted to be less dramatic
• Typo in greeting greeting_affectionate_enamored_crawling_back
• Fix some documentation

Closes #849 #853 #854

[Blizzardsev]

More testing is required before merging to try and replicate reports of weather changes making Natsuki play through her idles very quickly; I'm struggling to recreate this myself.

[Blizzardsev]

Going to merge this in; pretty confident it resolves the issue the best it can now that the root cause has been established.