Remove overlay filesystem functionality and add detection/removal capability

- Remove unused overlay filesystem configuration and references
- Remove overlayfs sections from all profile JSON files
- Remove OVERLAY_ENABLED/OVERLAY_PROTECT_CONFIGS from config
- Update documentation to focus on tmpfs optimization
- Add overlay detection and removal functionality for cleanup
- Add remove_overlays() function with safe unmounting
- Add overlay status reporting in final optimization summary
- Add test-overlay-detection.sh for testing detection logic
- Simplify codebase by removing complex unused features
- Focus on proven desktop optimizations (tmpfs, zram, kernel)

test-overlay-detection.sh

@@ -0,0 +1,113 @@
+#!/bin/bash
+# Test script to verify overlay detection and removal functionality
+# This script creates a temporary overlay mount and tests detection
+
+set -euo pipefail
+
+# Colors
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+BLUE='\033[0;34m'
+NC='\033[0m'
+
+log() {
+    echo -e "${BLUE}[TEST]${NC} $1"
+}
+
+success() {
+    echo -e "${GREEN}[SUCCESS]${NC} $1"
+}
+
+warn() {
+    echo -e "${YELLOW}[WARNING]${NC} $1"
+}
+
+error() {
+    echo -e "${RED}[ERROR]${NC} $1"
+}
+
+echo "🔍 Testing Overlay Detection Functionality"
+echo "=========================================="
+echo ""
+
+# Check if running as root (needed for mount operations)
+if [[ $EUID -eq 0 ]]; then
+    warn "Running as root - will test actual mount/unmount operations"
+    CAN_MOUNT=true
+else
+    log "Running as non-root - will test detection logic only"
+    CAN_MOUNT=false
+fi
+
+# Test 1: Check current overlay mounts
+log "Test 1: Checking for existing overlay mounts..."
+overlay_count=$(mount -t overlay 2>/dev/null | wc -l)
+if [[ $overlay_count -eq 0 ]]; then
+    success "No existing overlay mounts found (expected for desktop systems)"
+else
+    warn "Found $overlay_count existing overlay mounts:"
+    mount -t overlay | awk '{print "  " $3}'
+fi
+echo ""
+
+# Test 2: Test detection function (simulated)
+log "Test 2: Testing overlay detection logic..."
+cat << 'EOF'
+# This is what the detection code does:
+overlay_count=$(mount -t overlay | wc -l)
+if [[ $overlay_count -gt 0 ]]; then
+    echo "Found $overlay_count overlay mounts"
+    mount -t overlay | awk '{print "  " $3 " (overlay)"}'
+else
+    echo "No overlay mounts found"
+fi
+EOF
+
+echo ""
+log "Running detection logic:"
+if [[ $overlay_count -gt 0 ]]; then
+    echo "  ⚠️  Found $overlay_count overlay mounts (would suggest removal)"
+    mount -t overlay | head -3 | awk '{print "     " $3 " (overlay)"}' 
+else
+    echo "  ✅ No overlay mounts found (good - not needed for desktop)"
+fi
+echo ""
+
+# Test 3: Test temporary overlay creation (if root)
+if [[ $CAN_MOUNT == true ]]; then
+    log "Test 3: Creating temporary overlay for testing..."
+    
+    # Create temporary directories
+    mkdir -p /tmp/overlay-test/{lower,upper,work,merged}
+    echo "test content" > /tmp/overlay-test/lower/testfile.txt
+    
+    # Create overlay mount
+    if mount -t overlay overlay -o lowerdir=/tmp/overlay-test/lower,upperdir=/tmp/overlay-test/upper,workdir=/tmp/overlay-test/work /tmp/overlay-test/merged 2>/dev/null; then
+        success "Created test overlay mount at /tmp/overlay-test/merged"
+        
+        # Test detection again
+        new_overlay_count=$(mount -t overlay | wc -l)
+        log "Detection now shows: $new_overlay_count overlay mounts"
+        
+        # Clean up
+        log "Cleaning up test overlay..."
+        umount /tmp/overlay-test/merged 2>/dev/null || true
+        rm -rf /tmp/overlay-test
+        success "Test overlay cleaned up"
+    else
+        error "Failed to create test overlay (this is normal on some systems)"
+        rm -rf /tmp/overlay-test
+    fi
+else
+    log "Test 3: Skipped (requires root privileges)"
+fi
+
+echo ""
+success "Overlay detection test completed!"
+echo ""
+log "Summary:"
+echo "  • Overlay detection logic works correctly"
+echo "  • Current system has $overlay_count overlay mounts"
+echo "  • Desktop systems typically don't need overlay filesystems"
+echo "  • The optimizer will offer to remove any found overlays"