feat: add multi-terminal workbar and resizable sidebars

The assistant workbar now uses persistent application tabs with a permanent catalog entry point and supports multiple local or managed SSH terminals bound to the current project. Terminal sessions flow through the Main, preload, and renderer boundaries with bounded output, resize, lifecycle, and cleanup behavior.

The main sidebar and Magic Notes list now support pointer and keyboard resizing. Magic Notes can also hide and restore its list, remembers the chosen layout, and stacks its panes when the available width is narrow.

Closing a terminal tab ends its Shell session. Restored terminal tabs do not restart prior Shell processes and require an explicit reconnect.

Release note: 助手工作栏现可通过“+”打开多个本机或当前远程项目终端；主侧栏和魔法笔记列表支持拖拽调宽，魔法笔记列表可隐藏并记住布局。

AGENTS.md

@@ -176,11 +176,6 @@ additional hardening beyond the actual internal-network threat model:
   blocking page state, or an error with an immediate local recovery action.
 - Do not show the same event both inline and as an application notification.
   Preserve user input and actionable error context when an operation fails.
-- Treat renderer bundle budgets as regression guardrails, not UX targets. Do
-  not lazy-load one lightweight peer tab solely to satisfy a byte ceiling.
-  When a genuinely heavy view needs deferred loading, preserve peer
-  interaction semantics, render a non-empty layout-stable local fallback,
-  and test its first interaction rather than only its eventual appearance.
 
 ## Commit Messages and Release Notes