feat: Add enhanced EXI viewer with XML decode capability

- Implement complete CurrentDemandReq/CurrentDemandRes parsing (24 total fields)
- Add enhanced_exi_viewer.c with detailed message analysis
- Support -decode option for clean XML output (file-ready format)
- Enable ISO1, ISO2, DIN codec support in build configuration
- Fix C99 compatibility issues in makefiles (change -ansi to -std=c99)
- Create test utilities for hex string to EXI conversion
- Generate test files: test3.exi (CurrentDemandRes), test4.exi (CurrentDemandReq)

Features:
* Dual output modes: detailed analysis (default) vs XML (-decode)
* Complete V2G message type detection and parsing
* Session ID display in hex and ASCII formats
* Voltage/current/power readings with proper units
* All optional fields and status flags supported

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Release/sources.mk

@@ -0,0 +1,24 @@
+################################################################################
+# Automatically-generated file. Do not edit!
+################################################################################
+
+OBJ_SRCS := 
+ASM_SRCS := 
+C_SRCS := 
+S_UPPER_SRCS := 
+O_SRCS := 
+EXECUTABLES := 
+OBJS := 
+C_DEPS := 
+
+# Every subdirectory with source files must be described here
+SUBDIRS := \
+src/xmldsig \
+src/transport \
+src/test \
+src/iso2 \
+src/iso1 \
+src/din \
+src/codec \
+src/appHandshake \
+