Fix start.bat (ASCII-only, guaranteed window stays open) + add start.ps1

- start.bat: remove all Chinese characters (caused silent failure when
  Windows batch parser ran before chcp 65001 took effect); add :error
  label so window stays open with pause on any failure
- start.ps1: PowerShell alternative launcher with coloured output,
  works without worrying about cmd.exe encoding issues

Co-Authored-By: Claude Sonnet 4 <noreply@anthropic.com>

start.ps1

@@ -0,0 +1,111 @@
+# start.ps1 — Siemens RAGAS Console launcher for Windows PowerShell
+# Usage: Right-click -> "Run with PowerShell", or: powershell -ExecutionPolicy Bypass -File start.ps1
+
+$ErrorActionPreference = "Stop"
+Set-Location $PSScriptRoot
+
+Write-Host ""
+Write-Host "============================================================" -ForegroundColor Cyan
+Write-Host "  Siemens RAGAS Console  -  Starting..." -ForegroundColor Cyan
+Write-Host "============================================================" -ForegroundColor Cyan
+Write-Host ""
+Write-Host "Working directory: $PSScriptRoot"
+Write-Host ""
+
+# ----------------------------------------------------------------
+# 1. Check Python
+# ----------------------------------------------------------------
+try {
+    $pyver = & python --version 2>&1
+    Write-Host "[OK] $pyver" -ForegroundColor Green
+} catch {
+    Write-Host "[ERROR] Python not found. Please install Python 3.12+ and add to PATH." -ForegroundColor Red
+    Read-Host "Press Enter to exit"
+    exit 1
+}
+
+# ----------------------------------------------------------------
+# 2. Check FastAPI / uvicorn
+# ----------------------------------------------------------------
+$check = & python -c "import fastapi, uvicorn" 2>&1
+if ($LASTEXITCODE -ne 0) {
+    Write-Host "[INFO] Installing fastapi and uvicorn..." -ForegroundColor Yellow
+    & pip install fastapi uvicorn --quiet
+    if ($LASTEXITCODE -ne 0) {
+        Write-Host "[ERROR] Failed to install fastapi/uvicorn. Run: pip install fastapi uvicorn" -ForegroundColor Red
+        Read-Host "Press Enter to exit"
+        exit 1
+    }
+    Write-Host "[OK] fastapi / uvicorn installed." -ForegroundColor Green
+} else {
+    Write-Host "[OK] fastapi / uvicorn ready." -ForegroundColor Green
+}
+
+# ----------------------------------------------------------------
+# 3. Check ragas version
+# ----------------------------------------------------------------
+$check = & python -c "import ragas; assert ragas.__version__ == '0.4.3', ragas.__version__" 2>&1
+if ($LASTEXITCODE -ne 0) {
+    Write-Host "[INFO] Installing ragas==0.4.3 (evaluation engine)..." -ForegroundColor Yellow
+    & pip install "ragas==0.4.3" --quiet
+    if ($LASTEXITCODE -ne 0) {
+        Write-Host "[WARN] ragas install failed. Dashboard works; evaluation trigger will show error." -ForegroundColor Yellow
+    } else {
+        Write-Host "[OK] ragas 0.4.3 installed." -ForegroundColor Green
+    }
+} else {
+    Write-Host "[OK] ragas 0.4.3 ready." -ForegroundColor Green
+}
+
+# ----------------------------------------------------------------
+# 4. Seed demo data if missing
+# ----------------------------------------------------------------
+if (-not (Test-Path "outputs\kba-knowledge-base-offline-baseline")) {
+    Write-Host "[INFO] No run data found. Generating demo data..." -ForegroundColor Yellow
+    & python scripts\seed_sample_run.py
+    if ($LASTEXITCODE -ne 0) {
+        Write-Host "[WARN] Demo data generation failed. Dashboard may be empty." -ForegroundColor Yellow
+    } else {
+        Write-Host "[OK] Demo data generated." -ForegroundColor Green
+    }
+} else {
+    Write-Host "[OK] Run data found, skipping demo generation." -ForegroundColor Green
+}
+
+# ----------------------------------------------------------------
+# 5. Pick an available port
+# ----------------------------------------------------------------
+$PORT = 8800
+$inUse = netstat -ano 2>$null | Select-String ":$PORT\s" | Select-String "LISTENING"
+if ($inUse) {
+    Write-Host "[WARN] Port $PORT in use, trying 8801..." -ForegroundColor Yellow
+    $PORT = 8801
+    $inUse = netstat -ano 2>$null | Select-String ":$PORT\s" | Select-String "LISTENING"
+    if ($inUse) {
+        Write-Host "[ERROR] Ports 8800 and 8801 are both in use." -ForegroundColor Red
+        Write-Host "        Run manually: python webmain.py --port 8802"
+        Read-Host "Press Enter to exit"
+        exit 1
+    }
+}
+
+Write-Host ""
+Write-Host "============================================================" -ForegroundColor Cyan
+Write-Host "  Console URL : http://127.0.0.1:$PORT" -ForegroundColor Green
+Write-Host "  Press Ctrl+C to stop the server" -ForegroundColor Cyan
+Write-Host "============================================================" -ForegroundColor Cyan
+Write-Host ""
+
+# Open browser after 2-second delay
+Start-Job -ScriptBlock {
+    param($port)
+    Start-Sleep 2
+    Start-Process "http://127.0.0.1:$port"
+} -ArgumentList $PORT | Out-Null
+
+# Launch uvicorn (blocking)
+& python webmain.py --host 127.0.0.1 --port $PORT
+
+Write-Host ""
+Write-Host "Server stopped."
+Read-Host "Press Enter to exit"