Run quartodoc build against the refactored package (engine/ extracted from core/,
infra->infrastructure): regenerate the API reference so every stub points at the new
paths. Adds engine.*/infrastructure.* stubs, removes the 41 stale core.solver.* /
core.engine.* / core.scenarios.* / core.config.* / core.evaluation.* / infra*.qmd
orphans, and refreshes the package pages (core now primitives-only) + index.
Verified: all 47 documented symbols resolve in the new package; every index link
resolves; zero stale mlsysim.core.<engine-mod> / mlsysim.infra references anywhere in
docs/. (objects.json inventory is gitignored -- regenerated at build.)
