docs: add fall detection harness foundation

init.ps1

@@ -0,0 +1,34 @@
+#!/usr/bin/env pwsh
+
+# Silver Pose 的 Windows 统一启动与验证入口。
+# 当前阶段验证 demo 基线；T-101 创建 v1 后，应同步更新本文件和 docs/03-tech-stack.md。
+
+$ErrorActionPreference = "Stop"
+Set-Location -Path $PSScriptRoot
+
+$InstallCmd = 'python -c "import cv2, numpy, ultralytics, PyQt5; print(''required Python packages available'')"'
+$VerifyCmd = "python -m compileall -q demo"
+$StartCmd = "Set-Location demo; python main.py"
+
+function Invoke-Checked {
+  param([string]$Label, [string]$Command)
+  Write-Host "==> $Label"
+  Invoke-Expression $Command
+  if ($LASTEXITCODE -ne 0) {
+    throw "$Label failed with exit code $LASTEXITCODE"
+  }
+}
+
+Write-Host "==> 当前目录: $($PWD.Path)"
+Invoke-Checked -Label "检查 Silver Pose Python 依赖" -Command $InstallCmd
+Invoke-Checked -Label "运行 demo 基线验证" -Command $VerifyCmd
+
+Write-Host "==> 图形界面启动命令"
+Write-Host "    $StartCmd"
+
+if ($env:RUN_START_COMMAND -eq "1") {
+  Write-Host "==> 启动应用"
+  Invoke-Expression $StartCmd
+} else {
+  Write-Host "设置 RUN_START_COMMAND=1 后，init.ps1 会启动 GUI。"
+}