Major repository cleanup and enhancement

- Reorganize documentation: moved old docs to docs/ directory
- Add comprehensive README.md with build options and usage guide
- Add detailed CONTRIBUTING.md with help content management guide
- Create Makefile for automated building and testing
- Add Dockerfile.scratch for building from Ubuntu 20.04 base
- Enhance all Dockerfiles with PowerShell + PSScriptAnalyzer
- Add modern shells: zsh (with plugins) and fish (with config)
- Add modern CLI tools: fd-find, ripgrep, fzf
- Create comprehensive help system with cheat/TLDR/fish completions
- Add helper scripts for help content management and coverage checking
- Fix Dockerfile.remnux script references
- Support three build variants: upstream (REMnux), scratch (Ubuntu), kali

Build options:
  - make build-upstream: Fast, uses REMnux upstream (recommended)
  - make build-scratch: Full control, builds from Ubuntu 20.04
  - make build-kali: Legacy Kali Linux base

Features:
  - PowerShell with PSScriptAnalyzer module
  - Modern shells (zsh, fish) with custom configurations
  - Enhanced help system (cheat sheets, TLDR pages, fish completions)
  - Help coverage checking and bulk import tools
  - Comprehensive documentation for users and contributors

scripts/demo-help-coverage.sh

@@ -0,0 +1,64 @@
+#!/bin/bash
+
+# Simple demo to show current help coverage status
+
+echo "📚 Current Help System Status"
+echo "=============================="
+echo ""
+
+echo "📋 Available Cheat Sheets:"
+echo "-------------------------"
+ls -1 /opt/cheatsheets/personal/ 2>/dev/null | head -20 | sed 's/^/  ✅ /'
+echo ""
+
+echo "📖 Available TLDR Pages (custom):"
+echo "---------------------------------"
+ls -1 /home/remnux/.local/share/tldr/pages/common/*.md 2>/dev/null | \
+  sed 's|.*/||; s|\.md$||' | head -20 | sed 's/^/  ✅ /'
+echo ""
+
+echo "🧪 Testing fhelp cheat resolution:"
+echo "----------------------------------"
+echo "  Testing: fhelp cheat pdfid"
+fhelp cheat pdfid 2>&1 | head -5 | sed 's/^/    /'
+echo ""
+echo "  Testing: fhelp cheat pdfid.py (with .py)"
+fhelp cheat pdfid.py 2>&1 | head -5 | sed 's/^/    /'
+echo ""
+echo "  Testing: fhelp cheat oledump"
+fhelp cheat oledump 2>&1 | head -5 | sed 's/^/    /'
+echo ""
+
+echo "📊 Quick Check - Key Tools:"
+echo "--------------------------"
+
+KEY_TOOLS=("pdfid" "pdf-parser" "peepdf" "pdftk" "capa" "oledump" "binwalk" "strings")
+
+for tool in "${KEY_TOOLS[@]}"; do
+  cheat_status="❌"
+  tldr_status="❌"
+  
+  # Check cheat (simple file test)
+  if [[ -f "/opt/cheatsheets/personal/$tool" ]] || [[ -f "/opt/cheatsheets/personal/${tool}.py" ]]; then
+    cheat_status="✅"
+  fi
+  
+  # Check TLDR (simple file test)
+  if [[ -f "/home/remnux/.local/share/tldr/pages/common/${tool}.md" ]] || \
+     [[ -f "/home/remnux/.local/share/tldr/pages/common/${tool}.py.md" ]]; then
+    tldr_status="✅"
+  fi
+  
+  printf "  %-20s CHEAT: %s  TLDR: %s\n" "$tool" "$cheat_status" "$tldr_status"
+done
+
+echo ""
+echo "✨ Summary:"
+cheat_count=$(ls -1 /opt/cheatsheets/personal/ 2>/dev/null | wc -l)
+tldr_count=$(ls -1 /home/remnux/.local/share/tldr/pages/common/*.md 2>/dev/null | wc -l)
+echo "  📁 Cheat sheets: $cheat_count"
+echo "  📚 TLDR pages: $tldr_count"
+echo ""
+echo "💡 To add more tools:"
+echo "  1. Place remnux-tldr-cheatsheet.md in /data"
+echo "  2. Run: import-remnux-cheatsheets.sh /data/remnux-tldr-cheatsheet.md"