add DOCX support to Mermaid diagram rendering

- Transform.hs: DOCX case returns blocks unchanged (no unicode substitution needed)
- Mermaid.hs: DOCX uses PNG images at normal scale (like HTML, not 3x like PDF)

.gitignore

@@ -18,4 +18,5 @@ stack-setup-2.yaml
 analytics-charts.md
 architecture-deep-dive.md
 devcontainer.org
+.devcontainer/
 root.json

src/Docster/Mermaid.hs

@@ -79,6 +79,8 @@ generateDiagramPaths (DiagramConfig _ (OutputDir outDir) format) (DiagramId diag
                in (svgFile, T.pack $ takeFileName svgFile)
        PDF  -> let pngFile = outDir </> diagIdStr <> ".png"
                in (pngFile, T.pack pngFile)
+       DOCX -> let pngFile = outDir </> diagIdStr <> ".png"
+               in (pngFile, T.pack pngFile)
 
 -- | Puppeteer configuration content for disabling sandbox
 puppeteerConfigContent :: Text
@@ -90,6 +92,7 @@ callMermaidProcess format mmdFile outputFile = do
   let baseArgs = case format of
         HTML -> ["-i", mmdFile, "-o", outputFile]
         PDF  -> ["-i", mmdFile, "-o", outputFile, "--scale", "3"]
+        DOCX -> ["-i", mmdFile, "-o", outputFile]
   
   -- Create temporary puppeteer config file
   result <- bracket

src/Docster/Transform.hs

@@ -38,6 +38,7 @@ transformDocument config docName (Pandoc meta blocks) = do
       case dcOutputFormat config of
         PDF  -> return $ Right $ substituteUnicodeSymbols (Pandoc meta newBlocks)
         HTML -> return $ Right $ Pandoc meta newBlocks
+        DOCX -> return $ Right $ Pandoc meta newBlocks
 
 -- | Process a single block with heading tracking state
 processBlockStateful :: DiagramConfig -> Block -> TransformM Block