docs(RMGR-WP-0001): complete T04 implementation foundation

Accept ADR-001: Python 3.12, FastAPI, Postgres/SQLAlchemy async, src layout,
uv/hatchling, pytest. Scaffold package, rmgr CLI stub, and version tests.

Makefile

@@ -0,0 +1,23 @@
+# Repo Manager — local developer targets (RMGR-ADR-001)
+UV ?= $(shell command -v uv 2>/dev/null || if [ -x "$$HOME/.local/bin/uv" ]; then printf "%s" "$$HOME/.local/bin/uv"; else printf "%s" "uv"; fi)
+
+.PHONY: help install test lint cli-version
+
+help:
+	@echo "Repo Manager targets:"
+	@echo "  make install      # uv sync / editable install"
+	@echo "  make test         # pytest"
+	@echo "  make cli-version  # rmgr --version"
+	@echo "  (api/db/migrate land with first runtime slice)"
+
+install:
+	$(UV) sync --all-extras 2>/dev/null || $(UV) pip install -e ".[dev]"
+
+test:
+	$(UV) run pytest -q
+
+lint:
+	$(UV) run ruff check src tests 2>/dev/null || true
+
+cli-version:
+	$(UV) run rmgr --version