Integrated terminal: run shells inside MandoCode Desktop

[DevMando]

Summary

Adds a built-in terminal to MandoCode Desktop, so developers can run real shell commands (PowerShell, cmd, Git Bash, etc.) without leaving the app — the same way Visual Studio and VS Code let you pop open a terminal alongside your work.

Why this matters

Today, a user working with the AI agent has to alt-tab to a separate terminal window to run builds, git commands, or scripts. That context-switch is friction. Bringing the terminal into the app keeps the whole "chat with the agent → run a command → see the result" loop in one place, which is a core expectation for any serious developer tool.

What the user gets

• Open a terminal in one click — a terminal icon at the bottom of the left sidebar, or the keyboard shortcut Ctrl+** (the same shortcut VS Code uses). **Ctrl+Shift+ opens an additional shell.
• Slides up from the bottom, sharing the screen with the chat (the chat and input box move up to make room) — it does not cover the conversation.
• Resize it your way — drag the top edge up or down (the cursor changes to a resize arrow on hover), or use the maximize button to expand it to nearly full height and restore it back.
• Multiple shells, in tabs — open several terminals at once. The app automatically detects which shells are installed on the machine (PowerShell 7, Windows PowerShell, Command Prompt, Git Bash, WSL) and only offers the ones that are actually available.
• Opens in the right folder — each new terminal starts in the project folder of whichever agent tab you're currently working in.
• A real terminal, not a toy — colors, progress bars, and full-screen tools (like vim or interactive git) all work correctly, because it's built on the same underlying technology the Windows Terminal and VS Code use.

Scope / what's NOT in this change

• No changes to the AI agent, chat, settings, MCP, skills, or any existing feature — this is purely additive.
• The terminal is a manual tool for the user; the AI does not read from or type into it in this change.

Cost & risk notes (for planning)

• No new third-party dependencies or licensing to review at the package level — the terminal rendering library is bundled directly into the app and runs fully offline, consistent with the product's offline-first design. (The bundled library, xterm.js, is the same MIT-licensed component used by VS Code.)
• Nothing spins up until it's used — the terminal and its processes are only created the first time a user opens it, so there's no startup-time or memory cost for users who never touch it.
• Clean teardown — all shell processes are shut down when the app closes, so nothing is left running in the background.
• Windows-only, which is expected — this is the Windows desktop app.

How it was validated

• Builds clean (0 warnings, 0 errors).
• Verified end-to-end by launching the app and confirming a live PowerShell session runs inside the terminal (real shell + terminal backend processes confirmed running).
• Exercised open, maximize, resize, and multi-second stability runs.
• Two subtle Windows-UI startup crashes were found and fixed during development; the app now launches and runs stably.

Reviewer notes

• ~1,550 lines added across new files (terminal panel UI, shell/session management, the terminal backend, and the bundled web assets) plus small edits to the main window to host the panel and wire the shortcut.
• The bundled xterm.* files under Assets/web/terminal/ are the third-party library (expected to be large/minified); the reviewable app code is in Controls/, Services/, and MainWindow.*.