Improve High Tide AI usage

[vanja-ivancevic]

• We are preparing Fallen Empires Adventure dungeons whose authored AI decks use High Tide, which is currently excluded by AI:RemoveDeck:All.
• Add dedicated HighTide handling for its effect-based spell during the AI controller main phases, delegating payoff selection to the existing mana-ritual heuristic.
• Keep the card script schema-truthful. The AI derives the estimated net gain directly as the number of untapped Island lands minus the Island used to cast High Tide. This includes nonbasic lands with the Island subtype.
• Replace AI:RemoveDeck:All with AI:RemoveDeck:Random, allowing authored AI decks to use High Tide while keeping it out of generated decks that may lack sufficient Islands or worthwhile fixed-cost payoffs. This is especially important because High Tide also benefits opposing Islands.
• The existing ritual heuristic holds High Tide without a useful fixed-cost payoff and casts it when the additional mana unlocks one. X-cost spell planning remains outside this change.
• Verified with normal AI scenarios: with three Islands, Tundra, and Time Spiral, High Tide is selected first; without a payoff it is held; during an opponent main phase it is held. Existing Dark Ritual selection and mana-resolution scenarios also pass.