A third region state (contested frontline): a region in no nation's territory and not in unowned, opened/resolved by the LLM, tied to an active war. Sole-ownership invariant preserved. Durable GameState.contested; contested-inert stub; map legend stays at 7.
Adds the sea ability: a fixed set of 12 named sea zones with sole-control
semantics, contest-by-higher-military, and a deterministic per-turn
+1 military/+1 economy bonus for each claimed zone. Durable (owns
GameState.seaZones), additive migration, stub-inert (e2e unaffected).
Fixes#65
Design note: Gitea #65 sketched a free-form 'naval' layer; the implemented
approved design is this richer 'sea' layer with a fixed zone set.
Add the 10th modular LLM ability: a turn-transient TurnResult.migration
lever declaring population flows between nations (migration / refugees /
diaspora / exodus). The source loses a little population + economy, the
destination gains a little (a large influx also strains its stability),
and the from<->to relation is nudged one step toward the positive end of
the ally/neutral/rival/hostile ladder (capped by kind; a war is never
touched). Deterministic per-scale tables, no hidden randomness, clamped
0-100, mirrored to owned regions, re-derived aggregates; never moves
territory. Registered last in ABILITIES; user prompt unchanged
(user.txt golden byte-identical), system goldens re-baselined. Fixes#64.