Enhance FUSE detection for non-standard locations

Multi-stage detection strategy:
1. Try pkg-config (fastest, most reliable)
2. Search common header locations:
   - /usr/include, /usr/local/include
   - /opt/local/include, /opt/include
3. Compiler test as last resort:
   - Attempts to preprocess #include <fuse.h>
   - Tests both FUSE 3 and FUSE 2 versions

This handles:
- Minimal CI/CD environments (no pkg-config)
- Non-standard install locations (Homebrew, custom builds)
- Distro-specific paths (BSD, macOS, custom Linux)

The compiler test ensures detection works even when headers
are in unusual locations that gcc can find via its search paths.

detect_fuse.sh

@@ -2,25 +2,47 @@
 # Detect FUSE version and set appropriate flags
 
 # Check if pkg-config is available
-if ! command -v pkg-config >/dev/null 2>&1; then
-    # Fallback: check for header files
-    if [ -f /usr/include/fuse3/fuse.h ] || [ -f /usr/local/include/fuse3/fuse.h ]; then
+if command -v pkg-config >/dev/null 2>&1; then
+    # Use pkg-config if available
+    if pkg-config --exists fuse3 2>/dev/null; then
         echo "FUSE3"
-    elif [ -f /usr/include/fuse/fuse.h ] || [ -f /usr/local/include/fuse/fuse.h ]; then
+        exit 0
+    elif pkg-config --exists fuse 2>/dev/null; then
         echo "FUSE2"
-    else
-        echo "NONE"
-        exit 1
+        exit 0
     fi
-    exit 0
 fi
 
-# Use pkg-config if available
-if pkg-config --exists fuse3 2>/dev/null; then
-    echo "FUSE3"
-elif pkg-config --exists fuse 2>/dev/null; then
-    echo "FUSE2"
-else
-    echo "NONE"
-    exit 1
+# Fallback: search for header files in common locations
+SEARCH_PATHS="/usr/include /usr/local/include /opt/local/include /opt/include"
+
+for base in $SEARCH_PATHS; do
+    if [ -f "$base/fuse3/fuse.h" ]; then
+        echo "FUSE3"
+        exit 0
+    fi
+done
+
+for base in $SEARCH_PATHS; do
+    if [ -f "$base/fuse/fuse.h" ]; then
+        echo "FUSE2"
+        exit 0
+    fi
+done
+
+# Last resort: try to compile a test program
+if command -v gcc >/dev/null 2>&1; then
+    # Try FUSE 3
+    if echo '#include <fuse.h>' | gcc -E -DFUSE_USE_VERSION=30 - >/dev/null 2>&1; then
+        echo "FUSE3"
+        exit 0
+    fi
+    # Try FUSE 2
+    if echo '#include <fuse.h>' | gcc -E -DFUSE_USE_VERSION=26 - >/dev/null 2>&1; then
+        echo "FUSE2"
+        exit 0
+    fi
 fi
+
+echo "NONE"
+exit 1