Add NIP-42 implementation and local updates

- Added NIP-42 authentication implementation (nip042.c, nip042.h)
- Added NIP-42 test suite (nip42_test.c, nip42_test)
- Updated common core files for NIP-42 support
- Updated build script
- Rebuilt test binaries

build.sh

@@ -135,6 +135,7 @@ if [ "$HELP" = true ]; then
     echo "  011 - Relay information document"
     echo "  013 - Proof of Work"
     echo "  019 - Bech32 encoding (nsec/npub)"
+    echo "  042 - Authentication of clients to relays"
     echo "  044 - Encryption (modern)"
     echo ""
     echo "Examples:"
@@ -184,7 +185,7 @@ print_info "Auto-detecting needed NIPs from your source code..."
 NEEDED_NIPS=""
 if [ -n "$FORCE_NIPS" ]; then
     if [ "$FORCE_NIPS" = "all" ]; then
-        NEEDED_NIPS="001 004 005 006 011 013 019 044"
+        NEEDED_NIPS="001 004 005 006 011 013 019 042 044"
         print_info "Forced: Building all available NIPs"
     else
         # Convert comma-separated list to space-separated with 3-digit format
@@ -203,7 +204,7 @@ else
         # Check for nostr_core.h (includes everything)
         if grep -q '#include[[:space:]]*["\<]nostr_core\.h["\>]' *.c 2>/dev/null; then
             print_info "Found #include \"nostr_core.h\" - building all NIPs"
-            NEEDED_NIPS="001 004 005 006 011 013 019 044"
+            NEEDED_NIPS="001 004 005 006 011 013 019 042 044"
         elif [ -n "$DETECTED" ]; then
             NEEDED_NIPS="$DETECTED"
             print_success "Auto-detected NIPs: $(echo $NEEDED_NIPS | tr ' ' ',')"
@@ -221,7 +222,7 @@ fi
 
 # If building tests, include all NIPs to ensure test compatibility
 if [ "$BUILD_TESTS" = true ] && [ -z "$FORCE_NIPS" ]; then
-    NEEDED_NIPS="001 004 005 006 011 013 019 044"
+    NEEDED_NIPS="001 004 005 006 011 013 019 042 044"
     print_info "Building tests - including all available NIPs for test compatibility"
 fi
 
@@ -506,6 +507,7 @@ for nip in $NEEDED_NIPS; do
             011) NIP_DESCRIPTIONS="$NIP_DESCRIPTIONS NIP-011(Relay-Info)" ;;
             013) NIP_DESCRIPTIONS="$NIP_DESCRIPTIONS NIP-013(PoW)" ;;
             019) NIP_DESCRIPTIONS="$NIP_DESCRIPTIONS NIP-019(Bech32)" ;;
+            042) NIP_DESCRIPTIONS="$NIP_DESCRIPTIONS NIP-042(Auth)" ;;
             044) NIP_DESCRIPTIONS="$NIP_DESCRIPTIONS NIP-044(Encrypt)" ;;
         esac
     else