v0.99.0

v0.99.0 — Core simplification (behavior-preserving)

A quality pass across the Core engine (six file groups reviewed; every candidate adversarially verified for exact semantic equivalence). The Core is already clean — only two genuine simplifications cleared the bar, both verified by the full 1014-assertion test suite with no behavior change:

Under the hood

• GearParser — folded the whole-word, case-insensitive \b…\b match idiom (duplicated five times across item-type / rarity / Ancestral / charm-designation detection) into a single named WordIn helper.
• DiffEngine.EvalSlot — removed a redundant second pass over a slot's affixes: the "umbrella-covered" set is now tracked inline during the main matching loop instead of re-deriving it with a second MatchSlot walk (this runs once per gear slot on every render).

No functional changes; build is warning-free.