Fix puppeteer config to be portable across directories

- Embed puppeteer configuration in Mermaid module
- Create temporary config files instead of relying on external file
- Remove standalone puppeteer-config.json file
- Ensures docster works from any directory without config dependencies

🤖 Generated with [Claude Code](https://claude.ai/code)

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

puppeteer-config.json

@@ -1,3 +0,0 @@
-{
-  "args": ["--no-sandbox", "--disable-setuid-sandbox"]
-}

src/Docster/Mermaid.hs

@@ -16,8 +16,10 @@ import qualified Data.Text as T
 import qualified Data.Text.IO as TIO
 import Data.Hashable (hash)
 import System.FilePath (takeFileName, (</>))
-import System.Directory (removeFile)
+import System.Directory (removeFile, getTemporaryDirectory)
 import System.Process (callProcess)
+import System.IO (hClose)
+import System.IO.Temp (openTempFile)
 import Control.Exception (bracket, catch, SomeException)
 
 -- | Application constants
@@ -77,17 +79,30 @@ generateDiagramPaths (DiagramConfig (SourceDir sourceDir) format) (DiagramId dia
        PDF  -> let pngFile = sourceDir </> diagIdStr <> ".png"
                in (pngFile, T.pack pngFile)
 
+-- | Puppeteer configuration content for disabling sandbox
+puppeteerConfigContent :: Text
+puppeteerConfigContent = "{\n  \"args\": [\"--no-sandbox\", \"--disable-setuid-sandbox\"]\n}"
+
 -- | Call mermaid CLI process with appropriate arguments
 callMermaidProcess :: OutputFormat -> FilePath -> FilePath -> IO (Either DocsterError ())
 callMermaidProcess format mmdFile outputFile = do
   let baseArgs = case format of
         HTML -> ["-i", mmdFile, "-o", outputFile]
         PDF  -> ["-i", mmdFile, "-o", outputFile, "--scale", "3"]
-      args = baseArgs ++ ["--puppeteerConfigFile", "puppeteer-config.json"]
   
-  result <- catch
-    (callProcess (T.unpack mermaidCommand) args >> return (Right ()))
-    (\(e :: SomeException) -> return $ Left $ ProcessError $ "Mermaid process failed: " <> T.pack (show e))
+  -- Create temporary puppeteer config file
+  result <- bracket
+    (do tempDir <- getTemporaryDirectory
+        (configPath, configHandle) <- openTempFile tempDir "puppeteer-config.json"
+        hClose configHandle
+        TIO.writeFile configPath puppeteerConfigContent
+        return configPath)
+    (\configPath -> removeFile configPath `catch` \(_ :: SomeException) -> return ())
+    (\configPath -> do
+        let args = baseArgs ++ ["--puppeteerConfigFile", configPath]
+        catch
+          (callProcess (T.unpack mermaidCommand) args >> return (Right ()))
+          (\(e :: SomeException) -> return $ Left $ ProcessError $ "Mermaid process failed: " <> T.pack (show e)))
   return result
 
 -- | Create Pandoc image block from image path