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

Makefile

@@ -0,0 +1,93 @@
+.PHONY: help build-upstream build-scratch build-kali build-all test clean push
+
+# Default target
+help:
+	@echo "File Analysis Container - Build System"
+	@echo ""
+	@echo "Available targets:"
+	@echo "  build-upstream    Build from REMnux upstream image (recommended)"
+	@echo "  build-scratch     Build from Ubuntu 20.04 base (full control)"
+	@echo "  build-kali        Build from Kali Linux base (legacy)"
+	@echo "  build-all         Build all variants"
+	@echo "  test              Run tests on all builds"
+	@echo "  test-upstream     Test upstream build"
+	@echo "  test-scratch      Test scratch build"
+	@echo "  test-kali         Test Kali build"
+	@echo "  push              Push images to Docker Hub"
+	@echo "  clean             Remove all built images"
+	@echo ""
+
+# Build targets
+build-upstream:
+	@echo "Building REMnux upstream variant..."
+	docker build -f Dockerfile.remnux -t tabledevil/file-analysis:remnux .
+	@echo "✓ Build complete: tabledevil/file-analysis:remnux"
+
+build-scratch:
+	@echo "Building from scratch (Ubuntu 20.04 base)..."
+	docker build -f Dockerfile.scratch -t tabledevil/file-analysis:scratch .
+	@echo "✓ Build complete: tabledevil/file-analysis:scratch"
+
+build-kali:
+	@echo "Building Kali Linux variant..."
+	docker build -f Dockerfile -t tabledevil/file-analysis:kali .
+	@echo "✓ Build complete: tabledevil/file-analysis:kali"
+
+build-all: build-upstream build-scratch build-kali
+	@echo "✓ All variants built successfully"
+
+# Test targets
+test: test-upstream test-scratch test-kali
+	@echo "✓ All tests passed"
+
+test-upstream:
+	@echo "Testing REMnux upstream build..."
+	@docker run --rm tabledevil/file-analysis:remnux bash -c "which fhelp && fhelp cheat pdfid"
+	@docker run --rm tabledevil/file-analysis:remnux bash -c "which pdfid.py && which capa && which visidata"
+	@echo "✓ Upstream build tests passed"
+
+test-scratch:
+	@echo "Testing scratch build..."
+	@docker run --rm tabledevil/file-analysis:scratch bash -c "which fhelp && fhelp cheat pdfid"
+	@docker run --rm tabledevil/file-analysis:scratch bash -c "which pdfid.py && which capa"
+	@echo "✓ Scratch build tests passed"
+
+test-kali:
+	@echo "Testing Kali build..."
+	@docker run --rm tabledevil/file-analysis:kali bash -c "which pdfid.py && which capa"
+	@docker run --rm tabledevil/file-analysis:kali bash -c "which pwsh"
+	@echo "✓ Kali build tests passed"
+
+# Docker Hub push
+push:
+	@echo "Pushing images to Docker Hub..."
+	docker push tabledevil/file-analysis:remnux
+	docker push tabledevil/file-analysis:scratch
+	docker push tabledevil/file-analysis:kali
+	docker tag tabledevil/file-analysis:remnux tabledevil/file-analysis:latest
+	docker push tabledevil/file-analysis:latest
+	@echo "✓ Images pushed successfully"
+
+# Clean up
+clean:
+	@echo "Removing built images..."
+	-docker rmi tabledevil/file-analysis:remnux
+	-docker rmi tabledevil/file-analysis:scratch
+	-docker rmi tabledevil/file-analysis:kali
+	-docker rmi tabledevil/file-analysis:latest
+	@echo "✓ Cleanup complete"
+
+# Interactive shells for testing
+shell-upstream:
+	docker run -it --rm -v "$$(pwd):/data" tabledevil/file-analysis:remnux
+
+shell-scratch:
+	docker run -it --rm -v "$$(pwd):/data" tabledevil/file-analysis:scratch
+
+shell-kali:
+	docker run -it --rm -v "$$(pwd):/data" tabledevil/file-analysis:kali
+
+# Run help coverage check
+coverage:
+	@echo "Checking help coverage..."
+	docker run --rm tabledevil/file-analysis:remnux check-help-coverage.sh