feat(profile): advertise per-variant dictionary versions for offline preload

The Profile now carries dict_versions (game variant -> current dictionary
version), populated from the dictionary registry at the profileResponse
choke point, so an installed PWA can preload the matching dawg per enabled
variant off the existing cold-start profile request instead of adding a
round-trip for a rare feature.

Wire path: FBS DictVersion table + Profile.dict_versions (additive,
backward-compatible trailing field) -> backend dto/registry -> gateway
ProfileResp + FBS encoder -> client codec decode into a per-variant map on
model.Profile. Empty in a degenerate no-dictionary deployment; the mock
serves v1.3.0 for all three variants. Codec decode covered by a
bite-tested round-trip unit test.

ui/src/lib/model.ts

@@ -161,6 +161,10 @@ export interface Profile {
   /** Whether a Telegram / VK identity is attached — drives the Add / Unlink controls. */
   telegramLinked: boolean;
   vkLinked: boolean;
+  /** Current dictionary version per game variant (deployment-wide, not per-account). An
+   *  offline-capable PWA reads it to preload the matching dawg for each enabled variant off
+   *  this cold-start response. Empty only in a degenerate deployment with no resident dictionary. */
+  dictVersions: Partial<Record<Variant, string>>;
 }
 
 /** Banner is the advertising-banner block of an eligible viewer's profile. */