refactor(app-iced, presenter): M114 rebase 后守 400 行 —— 四处纯搬移（不动语义、不压注释、不挪断言）

主线六条合入后，四个被我碰过的文件越过 400 行；按模块拆开，只搬不改：

- `presenter/host/mod.rs` 421→366：账户刷新/皮肤三段（refresh_accounts / attach_skins /
  request_skins）搬进 `host/accounts/refresh.rs`（`impl CoreHost`，pub(in crate::host)）
- `presenter/state.rs` 410→392：`TileCell` + `grid_positions` 搬进 `state/tiles.rs`，
  `state.rs` 用 `pub use` 再导出，老路径不变
- `app-iced/app/state.rs` 401→394：账户页重建那一段搬进 `app/view/account_page.rs`
  的 `App::rebuild_account_page`
- `app-iced/app/update.rs` 407→388：`ULL_START_ROUTE` 取值表搬进 `app/update/boot_env.rs`
  （纯函数、无状态）

crates/presenter/src/host/mod.rs

@@ -37,8 +37,8 @@ use std::collections::{BTreeMap, BTreeSet, VecDeque};
 use std::time::Duration;
 
 use crate::dto::{
-    AccountKind, AccountView, AppCommand, AppEvent, Backend, CoreEvent, DiagnosisReport,
-    InstallProgressView, InstanceRuntime, JavaChainStep, NoticeView, SkinImage,
+    AccountView, AppCommand, AppEvent, Backend, CoreEvent, DiagnosisReport, InstallProgressView,
+    InstanceRuntime, JavaChainStep, NoticeView, SkinImage,
 };
 use crate::mock::MockBackend;
 use crate::toast::{Toast, ToastKind};
@@ -222,61 +222,6 @@ impl CoreHost {
         self.send(CoreEvent::InstancesChanged(instances));
     }
 
-    fn refresh_accounts(&mut self) {
-        self.accounts = accounts::accounts(&self.env, self.active_account.as_deref());
-        if self.active_account.is_none() {
-            // 默认选中第一个账户（没有账户时保持 None = 离线占位）
-            self.active_account = self.accounts.first().map(|account| account.id.clone());
-            self.accounts = accounts::accounts(&self.env, self.active_account.as_deref());
-        }
-        self.attach_skins();
-        self.request_skins();
-        self.send(CoreEvent::AccountsChanged(self.accounts.clone()));
-    }
-
-    /// 把已抓到的皮肤盖到账户视图上。
-    ///
-    /// 只盖第三方轨：离线档案没有皮肤，微软轨不做真头像（M114 口径）——
-    /// 「没有皮肤就画首字母块」，绝不给假皮肤/白块。
-    fn attach_skins(&mut self) {
-        for account in &mut self.accounts {
-            if account.kind != AccountKind::Authlib {
-                account.skin = None;
-                continue;
-            }
-            if let Some(skin) = self.skins.get(&account.id) {
-                account.skin = skin.clone();
-            }
-        }
-    }
-
-    /// 给还没抓过皮肤的第三方轨账户起后台抓取（每个账户只抓一次）。
-    ///
-    /// 抓不到就记 `None`：错误在面板上不显示（皮肤是装饰，不是业务失败），但也不会重试刷屏。
-    fn request_skins(&mut self) {
-        let mut pending = Vec::new();
-        for account in &self.accounts {
-            if account.kind != AccountKind::Authlib || account.server_url.trim().is_empty() {
-                continue;
-            }
-            if self.skin_requested.insert(account.id.clone()) {
-                pending.push((
-                    account.id.clone(),
-                    account.server_url.clone(),
-                    account.profile_id.clone(),
-                ));
-            }
-        }
-        for (id, server, profile) in pending {
-            let tx = self.tx.clone();
-            let env = self.env.clone();
-            job::spawn("account-skin", move || {
-                let skin = accounts::fetch_skin(&env, &server, &profile).ok();
-                let _ = tx.send(HostTask::Avatar { id, skin });
-            });
-        }
-    }
-
     fn refresh_java(&mut self) {
         let page = java::page(
             &self.env,