-15 mood is required to become "crazy", rather than -7 (#92449)

## About The Pull Request

`MOOD_LEVEL_SAD2` (-7 to -14) now brings you down to `SANITY_UNSTABLE`
at worse
`MOOD_LEVEL_SAD3` (-15 to -20) now brings you down to `SANITY_CRAZY` at
worse
`MOOD_LEVEL_SAD4` (-20 to -inf) now brings you down to `SANITY_INSANE`
(unchanged)

## Why It's Good For The Game

-7 to -14 puts you neatly in the threshold that a single moderately bad
thing happening to you will drive you completely crazy, which feels a
bit excessive and makes it difficult to have nuance with sanity levels.

This as a problem with sanity hallucinations in particular. These
hallucinations kick in when you're "crazy" or "insane", but being
moderately hungry is enough to dip into "crazy", which feels off and
excessive - you don't start seeing things because you skipped one
dinner.

If I instead modified the hallucinations to only trigger in "insane",
I'm then unable to have differing hallucinations based on just how
insane you are. So, modifying the threshold to afford more nuance here
(and maybe for other mechanics) is welcome.

Moving it to -15 to -20 means you need at least two moderate bad things
to start ticking towards crazy. For example, Freezing and suffocating to
death simultaneously would be enough to drive you crazy.

## Changelog

🆑 Melbert
balance: Mood threshold to become "crazy" changed from -7 (one
moderately bad event) to -15 (two moderately bad events).
/🆑

code/datums/mood.dm

@@ -81,9 +81,9 @@
 		if(MOOD_LEVEL_SAD4)
 			adjust_sanity(-0.3 * seconds_per_tick, SANITY_INSANE)
 		if(MOOD_LEVEL_SAD3)
-			adjust_sanity(-0.15 * seconds_per_tick, SANITY_INSANE)
+			adjust_sanity(-0.15 * seconds_per_tick, SANITY_CRAZY)
 		if(MOOD_LEVEL_SAD2)
-			adjust_sanity(-0.1 * seconds_per_tick, SANITY_CRAZY)
+			adjust_sanity(-0.1 * seconds_per_tick, SANITY_UNSTABLE)
 		if(MOOD_LEVEL_SAD1)
 			adjust_sanity(-0.05 * seconds_per_tick, SANITY_UNSTABLE)
 		if(MOOD_LEVEL_NEUTRAL)