fix(mcp-agent): correct modifier key-combo normalization (Error Input Format) + cap UI-tree recursion depth

[DieBurgerSouce]

Summary

Two independent fixes for the Windows MCP agent:

1. Modifier key-combos were broken in press_key / press_key_global.
2. The cached UI-tree walk can overflow the stack on deeply-nested windows.

---

1. Key-combo normalization (crates/terminator-mcp-agent/src/helpers.rs)

normalize_key wrapped the entire key string in braces when it didn't already
contain {, so the documented "Ctrl+Z" became "{Ctrl+Z}" — a single unknown
token that the uiautomation backend rejects:

-32002 "Failed to press key on focused element"
Platform-specific error: Error { code: 6, message: "Error Input Format" }

Every modifier combo (Ctrl+Z, Ctrl+A, Alt+F4, …) failed. The schema
docstrings also recommended a broken form ("{Ctrl}{V}"): a single letter
inside braces ({V}) is not a valid named key.

Fix: parse +-separated combos into valid uiautomation syntax —
modifiers → {Ctrl}/{Alt}/{Shift}/{Win}; a final single character → a
literal char held under the modifier ("{Ctrl}z"); a final named key → braced
("{Alt}{F4}"). Already-braced raw syntax and lone characters pass through
unchanged. This matches the behaviour of the existing, tested
translate_gemini_keys converter in terminator-computer-use.

Also corrects the misleading key docstrings for PressKeyArgs /
GlobalKeyArgs (src/utils.rs).

input	before	after
Ctrl+Z	{Ctrl+Z} ❌	{Ctrl}z ✅
Ctrl+Shift+S	{Ctrl+Shift+S} ❌	{Ctrl}{Shift}s ✅
Alt+F4	{Alt+F4} ❌	{Alt}{F4} ✅

2. UI-tree depth cap (crates/terminator/src/platforms/windows/tree_builder.rs)

build_node_from_cached_element recurses unbounded when the caller passes no
tree_max_depth. Deeply-nested windows overflow the native stack — Windows
terminates the process with 0xC00000FD (the exit code the npm wrapper already
special-cases and restarts on). Add cap_tree_depth() / SAFE_MAX_TREE_DEPTH
(50) and apply it in build_tree_with_cache so the cached walk is always
bounded, even with no explicit depth.

---

Testing

• Unit tests added for normalize_key (combos, single keys, passthrough) and
  cap_tree_depth. Verified red→green (breaking the fix fails the test).
• cargo test -p terminator-mcp-agent --lib / -p terminator-rs --lib pass.
• Empirical runtime check against a release build: press_key_global with
  Ctrl+N / Ctrl+A / Ctrl+W now return executed_without_error
  (key_pressed: "{Ctrl}n" etc.) where the previous build returned
  Error Input Format.

🤖 Generated with Claude Code