Move the 5 shared reference/id primitives (resolveNationRef, resolveRegionKey,
freshNationId, freshWarId, NEW_NATION_STATS) from engine.ts into the new
server/abilities/shared.ts (breaking the engine<->ability import cycle), and
add server/abilities/types.ts with the Ability<K> interface + AbilityCtx /
UserPromptCtx types that the 8 per-feature ability modules will implement.
engine.ts imports the helpers and re-exports them so existing callers
(server/index.ts, the unit tests) are untouched. Behavior is identical; all
511 unit tests, lint and typecheck stay green.
Adds deterministic golden fixtures (server/abilities/goldens/) pinning the
EXACT output of buildSystemPrompt (no-tool + tool modes) and buildUserPrompt
for a fixed wwii-1939 preset plus a crafted state that exercises every
optional payload branch (regions, frontier, frontierMilitary, takeoverRisks,
unowned, markers, wars, relations, trades, embargoes, resources, industry).
These are the target: the v0.40.0 modular ability registry (P2-P5) must
reproduce these byte-for-byte. Part of #74.
kamilkrzywda