infra!: made app runner-agnostic (poetry/uv) and optimized build process

Makefile

@@ -4,7 +4,8 @@
 
 # --- SETTINGS ---
 # Change to 'uv' when ready.
-RUNNER = poetry
+RUNNER ?= poetry
+export RUNNER
 
 # --- VARIABLES ---
 CORE_DIR     = brain
@@ -19,7 +20,7 @@ INSTALL_CMD = $(if $(filter uv,$(RUNNER)),sync,install)
 ARGS           = $(filter-out $@,$(MAKECMDGOALS))
 BUMP_CMD       = cd $(CORE_DIR) && $(RUNNER) run bump-my-version bump
 COMPOSE_CMD    = docker-compose
-DOCKER_CMD     = cd $(CORE_DIR) && docker build -t $(IMAGE_NAME):latest .
+DOCKER_CMD     = cd $(CORE_DIR) && docker build --build-arg RUNNER=$(RUNNER) -t $(IMAGE_NAME):latest .
 
 RUNNER_ADD     = cd $(CORE_DIR) && $(RUNNER) add
 RUNNER_HOOKS   = cd $(CORE_DIR) && $(RUNNER) run pre-commit install -c ../.pre-commit-config.yaml
@@ -195,7 +196,7 @@ shell: check-docker
 
 test: check-runner
 	@echo "$(T)🧪 Running tests...$(R)"
-	$(RUNNER_RUN) pytest $(ARGS)
+	$(RUNNER_RUN) pytest -n auto --dist=loadscope $(ARGS)
 
 up: check-docker
 	@echo "$(T)🚀 Starting Agent Media...$(R)"