Allow play without owning Minecraft using local accounts

[ChimeraAnt-DEV]

Summary

Removes the region/ownership gating that prevented users outside Greater China without a Microsoft account from using the launcher, so users can add local accounts and play on offline/cracked servers.

What changed

• AccountsManager.kt — Removed checkLimit() (the circumventLimit marker-file workaround, isInGreaterChina() region gate, and hasMicrosoftAccount() condition) and the _isOffline state. The current account is now preserved and selectable everywhere instead of being nulled out.
• AccountManageScreen.kt — The Add-Account button always opens the full login menu (Local / Microsoft / external auth server). Account items are always selectable.
• LauncherElements.kt — First-launch "no account" routing now always opens the full login menu (FirstLoginMenu.NORMAL).
• AccountManageViewModel.kt — Dropped the now-unused isOffline field from ProfileUiState.
• Strings (EN + zh-CN) — The account_logging_missing_client_id error no longer tells users to set up an Azure app and rebuild. It now says Microsoft sign-in is unavailable in this build and points to local accounts.
• README.md — Updated account documentation for local/cracked-server play.

Fix: launch crash for non-owner Microsoft accounts

An earlier revision of this PR also removed the ownership-based offline downgrade in GameLaunchFlow, which caused a crash (white screen) on every launch. That downgrade has been restored.

A Microsoft account without Minecraft ownership is constructed as an offline identity — locally derived UUID, no official profile, no valid session (createAccount() in MicrosoftAuthenticator.kt). Without the downgrade, accountType stayed Microsoft, so the launcher passed user_type=msa with a non-official token/UUID and skipped the offline Yggdrasil/authlib injector path, and the client crashed during session validation.

This downgrade is not ownership enforcement — it is required to launch such accounts at all. It applies only to Microsoft accounts explicitly flagged ownsMinecraft=false; local and auth-server accounts are unaffected.

Notes

• Official Mojang servers still verify ownership server-side; an unowned account cannot join them.
• No Android SDK/AGP toolchain was available in the development environment, so CI (Build APK) is the compile/runtime gate.