package .bin/ scripts as proper nix packages, delete .bin/

Packaged 14 scripts from .bin/ into packages/ with proper dependency
declarations (writers.writeDashBin/writeBashBin/writePython3Bin):
- 256color → two56color (terminal color chart)
- avesta.sed → avesta (Avestan transliteration)
- bvg.sh → bvg (Berlin transit disruptions)
- unicode → charinfo (Unicode character info)
- chunk-pdf → chunk-pdf (split PDFs by page count)
- csv2json → csv2json (CSV to JSON converter)
- fix-sd.sh → fix-sd (exFAT SD card recovery, improved output handling)
- json2csv → json2csv (JSON to CSV converter)
- mp3player-write → mp3player-write (audio conversion for MP3 players)
- mushakkil.sh → mushakkil (Arabic diacritization)
- nix-haddock-index → nix-haddock-index (GHC Haddock index generator)
- pdf-ocr.sh → pdf-ocr (OCR PDFs via tesseract)
- prospekte.sh → prospekte (German supermarket flyer browser)
- readme → readme (GitHub README as man page)

All added to overlay and packages output. .bin/ directory removed.

packages/mushakkil.nix

@@ -0,0 +1,13 @@
+# Add Arabic diacritics (tashkeel) to text via alsharekh.org
+{
+  writers,
+  curl,
+  jq,
+}:
+writers.writeDashBin "mushakkil" ''
+  ${curl}/bin/curl -sSL 'https://diac.alsharekh.org/Diac/DiacText' \
+    -H "Content-Type: application/json" \
+    --data-raw "$(${jq}/bin/jq --raw-input '{word: ., type: 1}')" \
+    --compressed \
+    | ${jq}/bin/jq -r .diacWord
+''