Initial commit: FoFreeXit Phase 1 (Viewer) + Phase 2 (Annotate)

PDF viewer (render/search/text-select/thumbnails/outline) and annotation
engine (Highlight/Underline/Strikeout/Square/FreeText/Note) over PDFium +
lopdf, with Unicode font embedding for Vietnamese text and undo/redo.

scripts/fetch-pdfium.ps1

@@ -0,0 +1,24 @@
+# Tải PDFium prebuilt (bblanchon/pdfium-binaries) cho Windows x64
+# và đặt pdfium.dll vào thư mục gốc workspace để ff-engine nạp được.
+#
+# Dùng: powershell -ExecutionPolicy Bypass -File scripts/fetch-pdfium.ps1
+
+$ErrorActionPreference = "Stop"
+$root = Split-Path -Parent $PSScriptRoot
+$pdfiumDir = Join-Path $root "pdfium"
+$tmp = Join-Path $env:TEMP "pdfium-win-x64.tgz"
+$url = "https://github.com/bblanchon/pdfium-binaries/releases/latest/download/pdfium-win-x64.tgz"
+
+Write-Output "Tải PDFium từ: $url"
+Invoke-WebRequest -Uri $url -OutFile $tmp -UseBasicParsing
+
+New-Item -ItemType Directory -Force -Path $pdfiumDir | Out-Null
+Write-Output "Giải nén vào: $pdfiumDir"
+tar -xzf $tmp -C $pdfiumDir
+
+$dll = Join-Path $pdfiumDir "bin\pdfium.dll"
+if (-not (Test-Path $dll)) { throw "Không tìm thấy pdfium.dll sau khi giải nén ($dll)" }
+
+# Copy pdfium.dll ra gốc workspace để bind_pdfium tìm thấy trong cwd.
+Copy-Item $dll (Join-Path $root "pdfium.dll") -Force
+Write-Output "Xong. pdfium.dll đã đặt tại gốc workspace: $(Join-Path $root 'pdfium.dll')"