Add targeted 1.20.2 hotbar click regression coverage

[Copilot]

The reported 1.20.2 failure was a disconnect on /inventory 0 click when left-clicking or right-clicking NBT-heavy equippable/hotbar items, with the server rejecting the Click Container packet as oversized. Current HEAD no longer reproduces that failure, so this change adds focused coverage for the exact regression path.

• Targeted regression coverage

  • Adds a dedicated integration script for the 1.20.2 hotbar click scenario:
    • equips named + enchanted hotbar items matching the issue shape
    • exercises both inventory 0 click 36 LeftClick and inventory 0 click 37 RightClick
    • verifies MCC remains connected and responsive after each click

• Issue-shaped fixture setup

  • Uses survival-mode inventory state with:
    • a named/enchanted sword in hotbar slot 36
    • a named/enchanted chestplate in hotbar slot 37
  • Keeps the setup close to the original failure mode instead of relying on generic inventory smoke coverage

• Regression signal

  • Asserts absence of the original disconnect/error signatures in MCC output, including oversized-packet decoder failures
  • Confirms post-click liveness through follow-up commands rather than only checking that the click command was sent

run_mcc_command "inventory 0 click 36 LeftClick"
run_mcc_command "hotbar_click_regression_leftclick_ok"

run_mcc_command "inventory 0 click 37 RightClick"
run_mcc_command "hotbar_click_regression_rightclick_ok"
run_mcc_command "debug state"