Fix converted filename

Mark it by default with a string from the config file.

Issue: 397

modules/joex/src/main/resources/reference.conf

@@ -328,6 +328,11 @@ docspell.joex {
     # as used with the rest server.
     chunk-size = 524288
 
+    # A string used to change the filename of the converted pdf file.
+    # If empty, the original file name is used for the pdf file ( the
+    # extension is always replaced with `pdf`).
+    converted-filename-part = "converted"
+
     # When reading images, this is the maximum size. Images that are
     # larger are not processed.
     max-image-size = ${docspell.joex.extraction.ocr.max-image-size}

modules/joex/src/main/scala/docspell/joex/process/ConvertPdf.scala

@@ -135,7 +135,11 @@ object ConvertPdf {
   ) = {
     val hint =
       MimeTypeHint.advertised(MimeType.pdf).withName(ra.name.getOrElse("file.pdf"))
-    val newName = ra.name.map(n => s"$n.pdf")
+    val newName =
+      ra.name
+        .map(FileName.apply)
+        .map(_.withExtension("pdf").withPart(cfg.convertedFilenamePart, '.'))
+        .map(_.fullName)
     ctx.store.bitpeace
       .saveNew(pdf, cfg.chunkSize, MimetypeHint(hint.filename, hint.advertised))
       .compile