feat: put ncp on PATH on both platforms; rename WSL reqs to Windows

Ports the ncp PATH work from upstream. Registering ncp as a shell-profile
function failed three ways on Windows: the default Restricted execution policy
blocks the profile itself, profiles don't exist outside PowerShell (cmd, Win+R,
Task Scheduler), and the self-elevating installer writes the admin's profile.

Windows now ships management/ncp.cmd and the installer appends management\ to
the Machine PATH via [Environment]::SetEnvironmentVariable -- never setx, which
truncates PATH at 1024 chars. A .cmd is exempt from the execution policy.

Linux symlinks /usr/local/bin/ncp -> management/nexus-cli.sh, falling back to
the old .bashrc function when sudo is unavailable.

Also renames requirements-wsl.txt to requirements-windows.txt and purges stale
WSL references, including vite.config.js's dev-server comment and
controlpanel.py's "Check WSLg." error string.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

management/controlpanel.py

@@ -80,7 +80,7 @@ class NexusControlPanel:
         self.root = root
         
         if os.name != 'nt' and not os.environ.get('DISPLAY'):
-            print("ERROR: No DISPLAY variable. Check WSLg.")
+            print("ERROR: No DISPLAY variable. Is an X session running?")
             sys.exit(1)
 
         self.root.title("Nexus Control Panel")
@@ -91,7 +91,7 @@ class NexusControlPanel:
             print(f"Icon load failed: {e}")
 
         if not sys.platform.startswith("linux"):
-            # Keep the custom borderless titlebar on Windows/WSL,
+            # Keep the custom borderless titlebar on Windows,
             # but allow normal stacking on Linux Mint.
             self.root.overrideredirect(True)
         self.root.configure(background="#1e1e1e")

management/ncp.cmd

@@ -0,0 +1,16 @@
+@echo off
+REM ncp - PATH entry point on Windows. A .cmd, not a .ps1, on purpose: PowerShell's
+REM execution policy governs .ps1 only, so this keeps working under the default
+REM Restricted policy and from cmd, Win+R, Task Scheduler and .lnk targets - none
+REM of which load a PowerShell profile. install-windows.ps1 puts this directory on
+REM the machine PATH. ncp.ps1 stays for pwsh-on-Linux, where there is no PATH shim.
+REM
+REM ASCII only, same rule as the .ps1 files - a test in tests/test_smoke.py enforces it.
+setlocal
+set "ROOT=%~dp0.."
+REM System Python fallback so backup/restore work before the venv exists; those
+REM delegate to the stdlib-only bin/sync.py. Mirrors the same fallback in ncp.ps1.
+set "PY=%ROOT%\Promethean\Scripts\python.exe"
+if not exist "%PY%" set "PY=python"
+"%PY%" "%ROOT%\management\ncp.py" %*
+exit /b %ERRORLEVEL%

management/ncp.ps1

@@ -2,8 +2,10 @@
 # file the Linux shell wrapper runs; this only picks an interpreter and forwards
 # the arguments.
 #
-# Windows: install-windows.ps1 registers this automatically. To do it by hand,
-# or to get ncp inside PowerShell on Linux, add to $PROFILE.CurrentUserAllHosts:
+# On Windows, ncp comes from management/ncp.cmd on the machine PATH instead (a
+# .cmd is not subject to the execution policy and works outside PowerShell too) -
+# install-windows.ps1 sets that up. This file is what gives ncp to pwsh on Linux,
+# where restore-linux.sh registers it in $PROFILE.CurrentUserAllHosts as:
 #
 #     function ncp { & "<repo>/management/ncp.ps1" @args }
 #

management/ncp.py

@@ -12,7 +12,7 @@ bin/restore-linux.sh, controlpanel.py, nexus-popup.py and nexus-app.sh all keep
 calling what they always called.
 
 psutil does the process work (cmdlines, pattern sweeps, port owners). It is
-declared in requirements-base.txt AND requirements-wsl.txt, so both boxes have
+declared in requirements-base.txt AND requirements-windows.txt, so both boxes have
 it - but it is imported lazily so `ncp backup`/`restore` still run before the
 venv exists, exactly as they did when they shelled out to sync.py.
 """