73e10d34e5
Test-first from here on (per request after Phase 2's backend commit): LinkCodeGenerator has a standalone test (common/src/test) written and confirmed failing before the implementation existed. common: LinkCodeGenerator produces a 6-character code from an unambiguous charset (excludes 0/O/1/I/L — it gets read off a chat line and typed back). BackendConnection grows sendLinkRequest (now actually implemented, was a Phase 1 stub), sendChatMessage, and setChatListener/ ChatListener for inbound web->game chat, all wired into DefaultBackendConnection's existing JSON wire protocol. forge-1_12_2: LinkCommand (/mcmapper link) generates a code, resolves online/offline from the server's actual auth mode (MinecraftServer#isServerInOnlineMode), and shows it to the player. Forge1122ChatBridge implements the inbound half (injects web chat into real in-game chat via the player list) — injectWaypointShare is a documented Phase 4 stub, same pattern as sendLinkRequest was in Phase 1. MCMapperMod hooks ServerChatEvent to forward in-game chat out and wires the chat listener to the bridge. Verified end-to-end against a live MCMapper-Backend instance through the real Java client (not a stand-in): a mod-generated link code correctly redeems via the backend's HTTP endpoint to an account with the mod- supplied username, and a browser chat message correctly round-trips all the way to the mod's live ChatListener callback.