Type Venom platform links

[MarkMcCaskey]

Splitting #2936 up into serial reviewable chunks. I'm going to leave this PR as a draft until I have time to provide more evidence beyond inferring from the static structure here. Hopefully by tonight / tomorrow night. I'll make some experiments and distill them as gecko codes to test it out in the game and confirm more about the naming here before this needs to be reviewed.

From Codex:

Model the platform target GObj, signed smash-taunt timer, and vertically ordered joints as a dedicated Ground variable payload.

[decomp-dev]

Report for GALE01 (96ebecb - 079bee4)

No changes

[ribbanya]

I think based on previous PRs your Claude already understands this, but if you look at any given StageCallbacks[], it's basically setting up an array of runtime-typed objects:

StageCallbacks grVe_StageCallbacks[16] = {
    {
        grVenom_80203F98, // GObj 0, callback 0
        grVenom_80203FC4, // GObj 0, callback 1
        grVenom_80203FCC, // GObj 0, callback 2
        grVenom_80203FD0, // GObj 0, callback 3
        0,
    },
    {
        grVenom_80206B94, // GObj 1, callback 0
        grVenom_80206BBC, // GObj 1, callback 1
        grVenom_80206BC4, // GObj 1, callback 2
        grVenom_80206BEC, // GObj 1, callback 3
        (1 << 29),
    },

With this in mind, we know that for any given set of callbacks (StageCallbacks struct), the same union member is used for GroundVars. Two StageCallbacks elements sharing the same GroundVars union member is probably quite common as well. Like in this case, you might be able to pick out multiple GObjs which are semantically venom_platform.