Split Card Bugs

### Bugs found while testing fixes:

- [x] Split cards can't be cast with flashback (although this at least no longer crashes) - already noted in the following issues: #4594 #6327 #6470

- [x] Armed // Dangerous cast with Council of the Absolute in play on "Armed" now has a _different_ incorrect cost. It's discounting before combining the costs, thus charging R + 3G, when the entire spell contains the name Armed and thus should be discounted post-combined-cost, resulting in a total cost of 2RG instead.

- [x] Likely related to the above, Thalia, Guardian of Thraben increases the cost of fused spells by {2} (once per half) instead of {1}. Costs should be combined for Fuse before taxes/discounts are applied. Probably the same issue in #6493.

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- [x] If you want to cast a fuse card with fuse, you have to select the fuse option twice.

- [x] If you name Armed with Council of the Absolute, then casting a fused Armed//Dangerous costs only 3G, when it should cost 2RG. You also don't get to choose a target for Armed, although if you only have one creature out, it will be chosen.

- [x] All split cards have weird text... but only while in the hand; not while in deck editor.

- [x] Trying to cast Armed//Dangerous from the yard after giving it flashback with Snapcaster mage threw a rollback error:

- [x] Casting Delay on a fused Wear // Tear resulted in time counters never coming off it. It just sat there with three counters every turn.