Add Phase 1 foundation: Go module, core types, DB infrastructure, config

Establish the project foundation with three packages:
- core: shared types (Header, Metadata, Value, ObjectType, UUID generation)
- db: SQLite migration framework, connection management (WAL, FK, busy
  timeout), transaction helpers (StartTX/EndTX), time conversion
- config: runtime configuration (DB path, blob store, Minio, gRPC addr)

Includes initial schema migration (001_initial.sql) with 13 tables covering
shared infrastructure, bibliographic data, and artifact repository. Full test
coverage for all packages, strict linting (.golangci.yaml), and Makefile.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Makefile

@@ -0,0 +1,101 @@
+# Makefile — exo build, test, lint, and release targets
+#
+# Usage:
+#   make build      — compile all binaries to bin/
+#   make test       — run tests with race detector
+#   make vet        — run go vet
+#   make lint       — run golangci-lint
+#   make all        — vet -> lint -> test -> build (CI pipeline)
+#   make generate   — regenerate protobuf stubs (requires protoc)
+#   make clean      — remove bin/ and generated artifacts
+
+# ---------------------------------------------------------------------------
+# Variables
+# ---------------------------------------------------------------------------
+MODULE     := git.wntrmute.dev/kyle/exo
+BINARIES   := exo exod
+BIN_DIR    := bin
+
+VERSION    := $(shell git describe --tags --always 2>/dev/null || echo dev)
+
+GO         := go
+GOFLAGS    := -trimpath
+LDFLAGS    := -s -w -X main.version=$(VERSION)
+CGO        := CGO_ENABLED=1
+CGO_TEST   := CGO_ENABLED=1
+
+# ---------------------------------------------------------------------------
+# Default target — CI pipeline: vet -> lint -> test -> build
+# ---------------------------------------------------------------------------
+.PHONY: all
+all: vet lint test build
+
+# ---------------------------------------------------------------------------
+# build — compile all binaries to bin/
+# ---------------------------------------------------------------------------
+.PHONY: build
+build:
+	@mkdir -p $(BIN_DIR)
+	@for bin in $(BINARIES); do \
+		echo "  GO BUILD  cmd/$$bin"; \
+		$(CGO) $(GO) build $(GOFLAGS) -ldflags "$(LDFLAGS)" \
+			-o $(BIN_DIR)/$$bin ./cmd/$$bin; \
+	done
+
+# ---------------------------------------------------------------------------
+# test — run all tests with race detector
+# ---------------------------------------------------------------------------
+.PHONY: test
+test:
+	$(CGO_TEST) $(GO) test -race -count=1 ./...
+
+# ---------------------------------------------------------------------------
+# vet — static analysis via go vet
+# ---------------------------------------------------------------------------
+.PHONY: vet
+vet:
+	$(GO) vet ./...
+
+# ---------------------------------------------------------------------------
+# lint — run golangci-lint
+# ---------------------------------------------------------------------------
+.PHONY: lint
+lint:
+	golangci-lint run ./...
+
+# ---------------------------------------------------------------------------
+# generate — regenerate protobuf stubs from proto/ definitions
+# Requires: protoc, protoc-gen-go, protoc-gen-go-grpc
+# ---------------------------------------------------------------------------
+.PHONY: generate
+generate:
+	$(GO) generate ./...
+
+# ---------------------------------------------------------------------------
+# clean — remove build artifacts
+# ---------------------------------------------------------------------------
+.PHONY: clean
+clean:
+	rm -rf $(BIN_DIR)
+
+# ---------------------------------------------------------------------------
+# install-local — install binaries to ~/.local/bin
+# ---------------------------------------------------------------------------
+.PHONY: install-local
+install-local: build
+	cp bin/* $(HOME)/.local/bin/
+
+# ---------------------------------------------------------------------------
+# Help
+# ---------------------------------------------------------------------------
+.PHONY: help
+help:
+	@echo "Available targets:"
+	@echo "  all        vet -> lint -> test -> build (CI pipeline)"
+	@echo "  build      Compile all binaries to bin/"
+	@echo "  test       Run tests with race detector"
+	@echo "  vet        Run go vet"
+	@echo "  lint       Run golangci-lint"
+	@echo "  generate   Regenerate protobuf stubs"
+	@echo "  clean      Remove build artifacts"
+	@echo "  install-local  Install binaries to ~/.local/bin"