Reduce the 1.7 tab to a single 1.7 Animations mod

[dsnsgithub]

The 1.7 tab is gone. Its features now live as a single, toggleable 1.7 Animations tile in the Mods tab, keeping only the wanted groups; everything else is removed along with the code behind it.

What's kept

Section	Options
Blocking/Item Using	10
Sneaking	6
Items (incl. Sprite Rendering, Item Positions)	18
Offsets / Eye Height	11

Master toggle

The mod has its own enabled switch on the tile, and OldAnimationsConfig.isEnabled() reads it instead of returning a constant true. Every feature already went through that check, so switching the mod off leaves 1.8.9 untouched while the individual options keep their values. Two places did not go through it, and now do:

• The witch held-item translation cancel is tied to Third Person Item Positions, like the rest of that layer's transforms.
• The water/lava/fire block items that 14w25a removed are no longer re-registered — the models backing them went away with the rest of the 1.7 model features.

Resource-reload bookkeeping tracks the effective value of Trapdoor Item Position and Jump Boost Potion Color, so flipping the master switch rebakes the trapdoor model and the potion colour cache too.

What's removed

Resources, Models, Textures, Sounds, Particles, Combat, GUI, Debug Overlay, Tab Overlay, Enchantment Glint and Hitbox — 82 options in total, plus the mixins, helper classes, assets and translations that existed only for them:

• 55 mixin/util classes deleted; ModelBakeryMixin trimmed to the trapdoor item variant the kept Trapdoor Item Position option needs, and the mixed-purpose mixins (ItemRendererMixin, MinecraftMixin, GameRendererMixin, EntityRendererMixin, EntityRenderDispatcherMixin, LivingEntityRendererMixin, ClientPlayNetworkHandlerMixin, ItemEntityRendererMixin, ItemModelShaperMixin, WornSkullLayerMixin) stripped to their surviving features.
• oldanimations.mixins.json regenerated (88 → 31 entries) and the now-dead AmbientOcclusionFace access widener entry dropped.
• Assets only reachable from removed features deleted (opaque leaves blockstates/models/textures, old skull models/textures, fast grass, fence gate inventory models, water/lava/fire item models).

Menu

MenuCatalog.Tab.ANIMATIONS is gone, so the menu is HUD / Mods / Settings (tab row narrowed to 3 columns), and the mod is named "1.7 Animations" with its groups rendered as inline sections.

Verification

./gradlew :1.8.9:build passes (compile, license headers, access widener validation). The dev client was launched headless and the menu walked through in game: three tabs, one 1.7 Animations tile with a working toggle (flipping it triggers the resource rebake and persists as "enabled": "false"), and all four sections present with their options. Every remaining injector was audited for the isEnabled() guard; the only ones without it capture render state, register the trapdoor model variant, or refresh the potion cache — none change vanilla behaviour.