[Feature] Add a maximize/expand shortcut for the terminal panel with user-customizable keybindings

Pre-submission checklist

• I searched existing issues and confirmed this isn't a duplicate (related: #529, which requests customizable shortcuts in general)
• I've read CONTRIBUTING.md

Category

UI / 界面体验 · UI / UX

Agent framework

ZCode Agent（自研） — this is about the built-in terminal panel in the ZCode desktop app itself.

Use case · 使用场景

1. Reading long agent output. When an agent is running long commands (builds, test suites, migrations), I want to read the streaming terminal output, so I maximize the terminal panel. Right now the only way to change the terminal height is to drag the divider with the mouse, every single time, and the layout doesn't stick.

2. Driving other coding agents from inside ZCode (the important one for me). I use the maximized terminal panel to run and manipulate a different coding agent CLI directly inside the ZCode window — so ZCode acts as the single cockpit where I orchestrate all my agents, its own and external ones. In that workflow the maximized terminal is the other agent's workspace: I expand it, work in that agent, then restore it to get back to the ZCode conversation — many times per hour. Each of those switches currently requires a manual mouse drag of the divider, which constantly breaks flow. This shortcut is genuinely load-bearing for that integration, not a nice-to-have.

The current shortcuts don't cover either case:

• Cmd+J toggles the terminal panel open/closed, but never changes its size
• Cmd+B / Option+Cmd+B collapse the side panes, but the chat/terminal split stays the same
• The official Keyboard Shortcuts docs list no command for maximizing or resizing the panel

Proposal · 建议方案

Two-part request:

1. Add a built-in "Toggle maximized terminal panel" command with a default shortcut — one keypress to expand the terminal to fill the window (and press again to restore), like VS Code's workbench.action.toggleMaximizedPanel. Double-clicking the panel divider to toggle maximize would also be welcome.
2. Make keyboard shortcuts customizable — a keybindings editor in Settings (UI, or a JSON settings file), so users can assign their own shortcut to this command and rebind other panel/window actions (e.g. the request in #529 to rebind Ctrl+B).

The first item alone would help; the second makes it future-proof for all shortcuts.

Expected value · 预期价值

• Inspecting long agent output becomes a single keystroke instead of a mouse drag each time
• Makes ZCode practical as a single cockpit for orchestrating multiple coding agents (its own + external CLIs) in one window — quick maximize/restore of the terminal is the core interaction in that workflow
• Supports keyboard-only workflows and VS Code muscle memory
• A keybindings editor resolves all future "please add/change this shortcut" requests at once

Your perceived priority

高 · High

ZCode version / environment

ZCode Desktop 3.9.2 (3.9.2.6069) · macOS 15.6 (24G84), Apple Silicon

Additional context

• Reference behavior: VS Code — workbench.action.toggleMaximizedPanel (View: Toggle Maximized Panel Size) and its Keyboard Shortcuts editor
• Official docs consulted: https://zcode.z.ai/en/docs/keyboard-shortcuts (lists Cmd+J, Cmd+B, Option+Cmd+B, Cmd+K — no maximize command)

The issue identifies the built-in terminal panel, existing Cmd+J behavior, keyboard-shortcuts documentation, and VS Code's View: Toggle Maximized Panel Size command, but names no source files or tests. Start by locating the desktop terminal-panel and shortcut-handling entry points. Done means a default maximize/restore shortcut works, and user-customizable keybindings are available as proposed.