Fix compilation issues: use static libcurl and improve includes

- Add curl include path from deps/curl/curl/include
- Link against static libcurl.a from deps
- Add zlib dependency (-lz) required by libcurl
- Use "" style includes for local headers (sqlite3.h, mysql.h, crypt.h, curl/curl.h)
- Rename sqlite_bind_text helper to bind_text to avoid collision with sqlite3_bind_text API
- Add comprehensive Doxygen documentation to rag_ingest.cpp

RAG_POC/Makefile

@@ -6,14 +6,18 @@ ROOT_DIR := ..
 INCLUDES := \
 	-I$(ROOT_DIR)/deps/json \
 	-I$(ROOT_DIR)/deps/mariadb-client-library/mariadb_client/include \
-	-I$(ROOT_DIR)/deps/sqlite3/sqlite-amalgamation-3500400
+	-I$(ROOT_DIR)/deps/sqlite3/sqlite-amalgamation-3500400 \
+	-I$(ROOT_DIR)/deps/curl/curl/include
 
 LIBDIRS := \
 	-L$(ROOT_DIR)/deps/mariadb-client-library/mariadb_client/libmariadb
 
 SQLITE3_OBJ := $(ROOT_DIR)/deps/sqlite3/sqlite-amalgamation-3500400/sqlite3.o
 
-LIBS := -lmariadbclient -lssl -lcrypto -lcrypt -ldl -lpthread
+# Use static libcurl
+CURL_STATIC_LIB := $(ROOT_DIR)/deps/curl/curl/lib/.libs/libcurl.a
+
+LIBS := -lmariadbclient -lssl -lcrypto -lcrypt -ldl -lpthread $(CURL_STATIC_LIB) -lz
 
 TARGET := rag_ingest
 SOURCES := rag_ingest.cpp