Fix nix flake and use gcc as compiler

Makefile

@@ -4,15 +4,14 @@ OBJ_DIR := build
 INCLUDE_DIR := include
 SCRIPT_DIR := scripts
 
-TARGET_DEBUG := $(BIN_DIR)/game-dbg
-TARGET_RELEASE := $(BIN_DIR)/game
+TARGET_DEBUG := $(BIN_DIR)/misth-dbg
+TARGET_RELEASE := $(BIN_DIR)/misth
 
 PCH_DEBUG := $(OBJ_DIR)/debug/pch.h.gch
 PCH_RELEASE := $(OBJ_DIR)/release/pch.h.gch
 
-CCACHE := ccache
-CXX := $(CCACHE) $(shell which clang++)
-CC := $(CCACHE) $(shell which clang)
+CC ?= gcc
+CXX ?= g++
 
 # ---------------- SDL3 ----------------
 
@@ -36,7 +35,6 @@ CFLAGS_DEBUG := \
 
 CFLAGS_RELEASE := \
 	-std=c++20 -O3 -mtune=generic \
-	-flto=thin \
 	-fno-rtti -fomit-frame-pointer -DNDEBUG -s \
 	-Wno-unused-command-line-argument \
 	-I./include -I./libs/mruby/build/host/include \
@@ -59,7 +57,7 @@ DEP_RELEASE := $(OBJ_RELEASE:.o=.d)
 
 .PHONY: all debug release clean scripts
 
-all: debug
+all: release
 
 debug: scripts $(TARGET_DEBUG)
 
@@ -68,7 +66,7 @@ release: scripts $(TARGET_RELEASE)
 # ---------------- MRB_MGEMS ----------------
 
 scripts:
-	$(SCRIPT_DIR)/compile.sh
+	bash $(SCRIPT_DIR)/compile.sh
 
 # ---------------- PCH ----------------
 
@@ -115,5 +113,5 @@ $(OBJ_DIR)/release/%.o: $(SRC_DIR)/%.cc $(PCH_RELEASE)
 
 clean:
 	@rm -rf $(OBJ_DIR) $(BIN_DIR)
-	$(SCRIPT_DIR)/compile.sh clean
+	bash $(SCRIPT_DIR)/compile.sh clean
 	@echo "Cleaned build artifacts."