refactor(cost-model): use linear costing for valueContains

[Unisay]

Summary

• Change valueContains costing from multiplied_sizes to const_above_diagonal with linear_in_x_and_y inner model
• Add LinearInXAndY constructor to SimpleJSON.hs for JSON parsing
• Update cost model visualization to support new model types

Motivation

The true complexity of valueContains is O(m*log(n/m+1)) where n is the container size and m is the contained size. Kenneth MacKenzie showed that this is bounded above by a linear function (m+n)/k for some constant k.

The new model better reflects this:

• Above diagonal (y > x): constant cost (early exit, returns False immediately)
• Below diagonal (x >= y): intercept + slope1*x + slope2*y

Changes

File	Change
models.R	Update valueContainsModel to use const_above_diagonal with linear_in_x_and_y
SimpleJSON.hs	Add LinearInXAndY constructor for JSON parsing
utils.js	Add evaluators for linear_in_x_and_y and const_above_diagonal
builtinCostModel{A,B,C}.json	Regenerated with new model type

New Cost Model Structure

"valueContains": {
  "cpu": {
    "arguments": {
      "constant": 284518,
      "model": {
        "arguments": {
          "intercept": 1000,
          "slope1": 158792,
          "slope2": 24659
        },
        "type": "linear_in_x_and_y"
      }
    },
    "type": "const_above_diagonal"
  },
  "memory": {
    "arguments": 32,
    "type": "constant_cost"
  }
}

Test plan

• [x] Build passes
• [x] Conformance tests pass (will need budget expectation updates)
• [x] Cost model visualization works with new model type

Closes https://github.com/IntersectMBO/plutus-private/issues/1984

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Built to branch gh-pages at 2025-12-04 16:06 UTC.
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[Unisay]

This PR replaces https://github.com/IntersectMBO/plutus/pull/7476