fix(trades): normalize the rate against deuterium like the other resources

[rolljee]

The bug

parseRate(rate, type) is documented as normalizing a rate against a reference resource. The metal and crystal branches do that — they divide the other two terms by the term being sold. The deut branch reads them raw:

} else if (type === 'deut') {
  res = { rateMetal: metal, rateCrystal: crystal, rateDeut: 1 };
}

A rate is a ratio, so 4:3:2 states exactly what 2:1.5:1 states. After this function it did not:

rate	sellMetal(1000)	sellDeut(1000)
2:1.5:1	{ deut: 200, crystal: 300 }	{ metal: 1200, crystal: 600 }
4:3:2 (before)	{ deut: 200, crystal: 300 }	{ metal: 2400, crystal: 1200 } ❌
4:3:2 (after)	{ deut: 200, crystal: 300 }	{ metal: 1200, crystal: 600 } ✅

Selling deuterium paid out scaled by the deuterium term. It only ever looked right because rates are conventionally written against 1 deuterium, which makes the division a no-op — every rate in the README, in the presets of ogame-ui and in !ogc on the Discord bot is of that form.

Found from the trade calculator in ogame-ui, whose custom-rate form lets you type any three numbers.

The fix

Divide by deut, like the other two branches divide by their own term. Two lines.

Compatibility

No change for any rate whose deuterium term is 1, which is every rate in the docs and every preset shipped by the callers. Only rates written against another scale move — and those were wrong.

Tests

• parseRate('4:3:2', 'deut') normalizes to { rateMetal: 2, rateCrystal: 1.5, rateDeut: 1 }.
• 4:3:2, 10:7.5:5 and 2:1.5:1 parse identically for all three reference resources.
• sellDeut(100000, 50, 50, '4:3:2') returns the same as at 2:1.5:1.

Lint, types and the 318 tests pass locally.

Noted, not fixed here

parseRate still accepts terms it cannot use: a 0 term divides by zero and comes back as Infinity, an empty one ('2::1') reads as 0, and a negative one yields negative resources — hasNaN catches none of the three. That is a separate change with a wider blast radius (it turns cases that return a number into throws), so it is left out of this patch. ogame-ui validates its input before calling.

🤖 Generated with Claude Code

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🎉 This PR is included in version 4.0.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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