Fix Failing Cycamore Unit Tests

[dean-krueger]

This PR primarily does two things:

1. Absorb now respects manual decay (previously it would decay things whenever you absorbed if you were in manual mode, which was causing the failing unit test in Cycamore).
2. Updates the logical flow of the decay-on-Absorb conditions to make them easier to read/understand (I added another condition to one of the if statements and it became so unwieldy I asked Codex if there was a way to simplify/clarify the logic and I think it's a LOT better now).

I clean-built Cyclus and Cycamore-main and ran both sets of tests and everything passes now.

[github-actions]

Downstream Build Status Report - d79e370 - 2026-06-19 08:15:01 +0000

Build FROM cyclus_20.04_apt/cyclus

• Cycamore: Success ✅
• Cymetric: Failure ❌

Build FROM cyclus_20.04_apt/cyclus --parallel

• Cycamore: Success ✅
• Cymetric: Failure ❌

Build FROM cyclus_20.04_conda/cyclus

• Cycamore: Success ✅
• Cymetric: Failure ❌

Build FROM cyclus_20.04_conda/cyclus --parallel

• Cycamore: Success ✅
• Cymetric: Failure ❌

Build FROM cyclus_22.04_apt/cyclus

• Cycamore: Success ✅
• Cymetric: Failure ❌

Build FROM cyclus_22.04_apt/cyclus --parallel

• Cycamore: Success ✅
• Cymetric: Failure ❌

Build FROM cyclus_22.04_conda/cyclus

• Cycamore: Success ✅
• Cymetric: Failure ❌

Build FROM cyclus_22.04_conda/cyclus --parallel

• Cycamore: Success ✅
• Cymetric: Failure ❌

Build FROM cyclus_24.04_apt/cyclus

• Cycamore: Success ✅
• Cymetric: Failure ❌

Build FROM cyclus_24.04_apt/cyclus --parallel

• Cycamore: Success ✅
• Cymetric: Failure ❌

Build FROM cyclus_24.04_conda/cyclus

• Cycamore: Success ✅
• Cymetric: Failure ❌

Build FROM cyclus_24.04_conda/cyclus --parallel

• Cycamore: Success ✅
• Cymetric: Failure ❌

[gonuke]

Thanks @dean-krueger - glad it turned out to be something that was relatively self-contained