refactor: move user-facing scripts to repo root; fix set-password ordering

- install-autostart.bat, uninstall-autostart.bat, restart-autostart.bat,
  open-firewall.bat moved from scripts/ to the repo root (next to run.bat and
  set-password.bat). Internal helpers (autostart-run.bat, ensure-vnc-password.ps1,
  get-novnc.*, get-vnc.ps1, list-ips.ps1) stay in scripts/. autostart-run.bat is
  kept in scripts/ because the scheduled task /TR points at it; moving it would
  break already-installed tasks.
- Updated all references (set-password.bat, run.bat, install/restart-autostart.bat,
  AGENTS.md, README.md).
- set-password.bat: write webvnc.conf BEFORE the UltraVNC sync so the web password
  is configured even if ensure-vnc-password.ps1 fails / its UAC is dismissed
  (previously 'Password is not configured' from install-autostart.bat when the
  sync blocked before conf was written).
- AGENTS.md / README.md structure + autostart sections updated for the new layout.

install-autostart.bat

@@ -0,0 +1,48 @@
+@echo off
+REM ============================================================
+REM  install-autostart.bat - register web-vnc as a startup task.
+REM  Creates a scheduled task "web-vnc" that runs at system startup
+REM  (as SYSTEM, highest privileges) and launches
+REM  scripts\autostart-run.bat in the foreground.
+REM  Requires administrator rights (auto-elevates).
+REM  Run set-password.bat first to configure the password.
+REM ============================================================
+cd /d "%~dp0"
+
+REM Admin check + auto-elevate.
+net session >nul 2>nul
+if errorlevel 1 (
+  echo Requesting administrator rights ...
+  powershell -Command "Start-Process -FilePath '%~f0' -Verb RunAs"
+  exit /b
+)
+
+if not exist "webvnc.conf" (
+  echo [error] Password is not configured. Run set-password.bat first.
+  pause
+  exit /b 1
+)
+if not exist "scripts\autostart-run.bat" (
+  echo [error] scripts\autostart-run.bat not found.
+  pause
+  exit /b 1
+)
+
+set "TASK=web-vnc"
+set "CMD=%~dp0scripts\autostart-run.bat"
+
+echo Creating scheduled task "%TASK%" (startup, SYSTEM, highest) ...
+schtasks /Create /TN "%TASK%" /TR "cmd /c \"%CMD%\"" /SC ONSTART /RU SYSTEM /RL HIGHEST /F
+if errorlevel 1 (
+  echo [error] Could not create the task.
+  pause
+  exit /b 1
+)
+
+echo.
+echo Done. web-vnc will start automatically on every boot.
+echo Start it now (without rebooting):
+echo   schtasks /Run /TN "%TASK%"
+echo Remove it with: uninstall-autostart.bat
+echo.
+pause