Add config module: INI loader with schema-driven defaults

Config_Def schema tables declare section/key/type/default per module.
Typed getters: config_get_str, _u16, _u32, _flags.
FLAGS type parses space/comma-separated tokens via a Config_Flag_Def table.
config_defaults() gives schema defaults without a file.
config_dump() prints effective values for diagnostics.

config_cli: load a file or --defaults and dump effective config.
dev/example.cfg: sample config covering node, discovery, transport.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/modules/config/Makefile

@@ -0,0 +1,17 @@
+ROOT := $(abspath ../../..)
+include $(ROOT)/common.mk
+
+MODULE_BUILD = $(BUILD)/config
+
+.PHONY: all clean
+
+all: $(MODULE_BUILD)/config.o
+
+$(MODULE_BUILD)/config.o: config.c $(ROOT)/include/config.h | $(MODULE_BUILD)
+	$(CC) $(CFLAGS) -c -o $@ $<
+
+$(MODULE_BUILD):
+	mkdir -p $@
+
+clean:
+	rm -f $(MODULE_BUILD)/config.o