docs(readme): 按用户令删除全部离线档案描述；门禁口径改为 main 推送 + PR

- 合规条里「Offline profiles cannot play online / 本地离线档案仅限本地与隔离网络测试」整条删除，
  只保留正面陈述「联机游玩需要 Microsoft 账户与有效的游戏权益」
- 模块地图 auth 行去掉「local offline profiles / 本地离线档案」，只留 Microsoft 正版登录全链路
- 全文 grep offline|离线|隔离网络 零命中；不做「不支持离线」的反向承诺，也不暗示别的账户通道
- 顺手修 nit：CI 段「Every push」→「Every push to main and every pull request」
  （ci.yml on.push 限 main 分支，非 main 且无 PR 时门禁不跑）

README.md

@@ -17,9 +17,7 @@ attached to other agent tooling as an MCP server.
   entitlement. There is no other account provider.
 - **Credentials stay on your machine.** Account tokens are stored locally only, are never sent to
   any server operated by this project, and the AI features cannot read them.
-- **Playing online requires a Microsoft account.** A local offline profile performs no Microsoft
-  authentication and contacts no Microsoft or Mojang service; it exists for local and
-  isolated-network testing only and is not an online-play path.
+- **Online play requires a Microsoft account and a valid game entitlement.**
 - ULL does not distribute, mirror, proxy or modify any Minecraft game files.
 - Not affiliated with Mojang or Microsoft.
 
@@ -109,7 +107,7 @@ The eight modules of `crates/core`:
 | `download` | multi-source health scoring, mirrors, chunked downloads, hash-while-downloading |
 | `game` | version / instance repository, snapshots and inheritance resolution |
 | `launch` | 10-stage launch pipeline, processes, JSONL event stream |
-| `auth` | Microsoft sign-in / local offline profiles |
+| `auth` | Microsoft sign-in (OAuth 2.0 device code → Xbox Live → XSTS → Minecraft Services) |
 | `addon` | mod loader installation, modpacks, CurseForge / Modrinth |
 | `diagnose` | five signal collectors, YAML rule engine, hs_err parsing |
 | `platform` | OS abstraction: paths, processes, file locks, capability probing, runtime OS detection |
@@ -153,10 +151,11 @@ Dependency license check (optional locally, required in CI):
 
 ## CI gates
 
-Every push runs fmt / clippy (warnings are errors) / the full test suite, and the Linux headless
-render smoke is a hard gate on the same footing: a red result blocks the merge. The macOS runtime
-probe is not there yet — it only runs on a manual `workflow_dispatch` and its result is recorded,
-not enforced (`continue-on-error`), until the slot passes a first run on a real runner.
+Every push to `main` and every pull request runs fmt / clippy (warnings are errors) / the full test
+suite, and the Linux headless render smoke is a hard gate on the same footing: a red result blocks
+the merge. The macOS runtime probe is not there yet — it only runs on a manual `workflow_dispatch`
+and its result is recorded, not enforced (`continue-on-error`), until the slot passes a first run on
+a real runner.
 
 | Workflow | Content |
 |----------|---------|