feat: uninstall the Chat GUI without removing the agent (CLI + desktop UI) (#40355)

* feat: uninstall the Chat GUI without removing the agent (CLI + desktop UI)

Adds a GUI-only uninstall path so people can remove the desktop Chat GUI
while keeping the Hermes agent + their config/sessions/.env, and surfaces
the three CLI uninstall modes inside the desktop app's Settings → About.

CLI:
- New hermes_cli/gui_uninstall.py: cross-platform discovery + removal of the
  desktop GUI's artifacts (source-built dist/release/node_modules + build
  stamp, the packaged app bundle, and the Electron userData dir) on Linux,
  macOS, and Windows. Never touches the agent source, venv, or user data.
- `hermes uninstall --gui` removes only the Chat GUI; `--gui-summary` prints a
  JSON install snapshot (used by the desktop UI to gate options + detect a
  missing agent for a future lite client).
- `hermes uninstall --yes` / `--full --yes` now run non-interactively, sharing
  the destructive sequence via a new _perform_uninstall() helper. The keep-data
  and full flows also sweep the GUI artifacts.

Desktop:
- electron/desktop-uninstall.cjs: pure helpers mapping each mode (gui/lite/full)
  to CLI flags, resolving the running app bundle per OS, and building the
  detached cleanup script that waits for the app to exit, runs the Python
  uninstall, and removes the bundle.
- IPC hermes:uninstall:summary / :run, preload bridge, and types.
- Settings → About "Danger zone" with the three options; agent-removing
  options hide when no local agent is detected.

Tests: tests/hermes_cli/test_gui_uninstall.py (22 pass with the existing
uninstall tests), electron/desktop-uninstall.test.cjs (17 pass, wired into
test:desktop:platforms). Docs: desktop.md "Uninstalling" + cli-commands.md.

* fix(desktop): tear down backend process tree before GUI uninstall (Windows lock safety)

The desktop uninstall cleanup script waited only on the desktop app's own
PID, but a backend grandchild (gateway / pty terminal / hermes REPL) can
outlive it and keep hermes.exe + venv files mandatory-locked on Windows —
making the script's rmdir half-fail and leaving a partial install, the same
failure class as the self-update path's #37532.

- main.cjs: runDesktopUninstall now awaits releaseBackendLock() before
  spawning the cleanup script — tree-kills every backend PID the desktop owns
  (primary + pool) via taskkill /T /F and polls the venv shim until unlocked.
  Extracted the shared core out of releaseBackendLockForUpdate so both the
  update hand-off and the uninstaller use the identical, incident-hardened
  teardown. No-op on macOS/Linux (no mandatory locks).
- desktop-uninstall.cjs: Windows cleanup script removes the bundle via a
  bounded rmdir retry loop (10x, 1s) instead of a single rmdir, since Windows
  releases directory handles lazily even after the holding process exits.
- Dropped a fragile tasklist|findstr reap-by-path attempt; the Electron-side
  tree-kill-by-PID is the reliable mechanism.

Tests: desktop-uninstall.test.cjs updated for the retry-loop output (17 pass).

* fix(desktop): address review on GUI uninstall (venv self-delete, gates, wait-loop)

Resolves @OutThisLife's review on #40355:

1. full mode now gated on agent presence (needsAgent: true). It removes the
   agent + user data, so on a lite client with no local agent it's hidden
   like lite — no more offering to remove an agent that isn't there.

2. (Finding 3, the real bug) lite/full no longer rmtree the venv from the
   venv's OWN python. On Windows a running python.exe is mandatory-locked, so
   that half-fails. New lightweight 'python -m hermes_cli.uninstall --mode X'
   entrypoint (stdlib-only imports) lets the desktop run agent-removing modes
   under the SYSTEM python (findSystemPython) with PYTHONPATH=<agentRoot>, so
   import hermes_cli resolves from source while the venv is torn down. Falls
   back to venv python + logs when no system python (gui-only unaffected).

3. Windows wait-loop is now bounded (60 tries, matching POSIX) and matches the
   PID as a whole space-delimited token via findstr (no substring 99->990
   trap, no redundant bare find). set HERMES_HOME/PID/PYTHONPATH now quoted.

4. Renamed the misleading 'returns null for dev run' test — the dev-run safety
   is shouldRemoveAppBundle(isPackaged=false), which the test now asserts.

Docs: note that --gui on a source checkout also sweeps node_modules/build
output. Tests: 18 python + 19 desktop pass.

hermes_cli/main.py

@@ -6697,8 +6697,30 @@ def cmd_version(args):
 
 
 def cmd_uninstall(args):
-    """Uninstall Hermes Agent."""
-    _require_tty("uninstall")
+    """Uninstall Hermes Agent (or just the Chat GUI with --gui)."""
+    # Machine-readable install snapshot for the desktop app's uninstall UI.
+    # Must run before any TTY gate — it's called from a non-interactive child.
+    if getattr(args, "gui_summary", False):
+        from hermes_cli.gui_uninstall import gui_install_summary
+
+        print(json.dumps(gui_install_summary()))
+        return
+
+    # GUI-only uninstall. The desktop app shells out to this non-interactively
+    # with --yes, so only gate on a TTY when we actually need to prompt.
+    if getattr(args, "gui", False):
+        if not getattr(args, "yes", False):
+            _require_tty("uninstall --gui")
+        from hermes_cli.uninstall import run_gui_uninstall
+
+        run_gui_uninstall(args)
+        return
+
+    # Full/keep-data uninstall. ``--yes`` runs non-interactively (the desktop
+    # app's lite/full modes drive this from a detached cleanup script), so only
+    # gate on a TTY when we actually need to prompt for the option + confirm.
+    if not getattr(args, "yes", False):
+        _require_tty("uninstall")
     from hermes_cli.uninstall import run_uninstall
 
     run_uninstall(args)
@@ -15454,6 +15476,17 @@ Examples:
         action="store_true",
         help="Full uninstall - remove everything including configs and data",
     )
+    uninstall_parser.add_argument(
+        "--gui",
+        action="store_true",
+        help="Uninstall only the desktop Chat GUI, leaving the agent intact",
+    )
+    uninstall_parser.add_argument(
+        "--gui-summary",
+        action="store_true",
+        help="Print a JSON summary of installed GUI/agent artifacts and exit "
+        "(used by the desktop app to gate uninstall options)",
+    )
     uninstall_parser.add_argument(
         "--yes", "-y", action="store_true", help="Skip confirmation prompts"
     )