Feat/v3 go rewrite (#47)

Complete rewrite of ArtifactAPI from Python/FastAPI to Go as a single binary.

Core engine:
- 10 package providers: generic, docker, helm, pypi, npm, rpm, alpine,
  puppet, terraform, goproxy — each with built-in mutable patterns
- Content-addressable storage (SHA256 dedup across all remotes)
- Three-tier caching: Redis (TTL/locks) → S3/MinIO (blobs) → upstream
- Classifier with allowlist/blocklist per-remote (empty = allow all)
- Circuit breaker, conditional revalidation, stale-on-error
- Background garbage collection for orphaned blobs
- Access logging to PostgreSQL

API:
- v1 proxy endpoints (backwards compatible)
- v2 management API: CRUD remotes/virtuals, object browser, stats,
  health, SSE events, probe/test endpoint
- Virtual repos with index merging (Helm YAML + PyPI HTML)

Frontend (React + Vite, separate Dockerfile):
- Dashboard with stats, health indicators, top remotes
- Remotes list with type filter, remote detail with config/patterns
- Object browser with pagination and evict
- Test Remote page: probe any remote path, see headers/size/timing
- Virtuals page with expandable member lists

TUI (Bubble Tea):
- Dashboard, remotes list/detail, object browser, virtuals
- Vim-style navigation, artifactapi tui --endpoint <url>

Infrastructure:
- S3 client supports MinIO, Ceph RGW, AWS S3 (minio-go)
- PostgreSQL schema with migrations
- Docker Compose: API + UI + Postgres 17 + Redis 7 + MinIO
- Makefile with Go version check, build/test/lint/fmt/e2e targets
- Distroless Docker image (~15MB)

Testing:
- Unit tests for models, classifier, providers, mergers
- E2E tests with testcontainers-go (real Postgres/Redis/MinIO)

Terraform config:
- All 40 production remotes + helm virtual as HCL
- Provider repo: terraform-provider-artifactapi v0.0.1 (separate)

---------

Co-authored-by: Ben Vincent <ben@unkin.net>
Reviewed-on: #47

e2e/helpers_test.go

@@ -0,0 +1,109 @@
+//go:build e2e
+
+package e2e
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"strings"
+	"testing"
+)
+
+func findListener() (net.Listener, error) {
+	return net.Listen("tcp", "127.0.0.1:0")
+}
+
+func apiURL(path string) string {
+	return baseURL + path
+}
+
+func createRemote(t *testing.T, body string) {
+	t.Helper()
+	resp, err := http.Post(apiURL("/api/v2/remotes"), "application/json", strings.NewReader(body))
+	if err != nil {
+		t.Fatalf("create remote: %v", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusCreated {
+		b, _ := io.ReadAll(resp.Body)
+		t.Fatalf("create remote: status %d: %s", resp.StatusCode, b)
+	}
+}
+
+func deleteRemote(t *testing.T, name string) {
+	t.Helper()
+	req, _ := http.NewRequest(http.MethodDelete, apiURL("/api/v2/remotes/"+name), nil)
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatalf("delete remote: %v", err)
+	}
+	resp.Body.Close()
+}
+
+func getJSON(t *testing.T, url string) map[string]any {
+	t.Helper()
+	resp, err := http.Get(url)
+	if err != nil {
+		t.Fatalf("GET %s: %v", url, err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		b, _ := io.ReadAll(resp.Body)
+		t.Fatalf("GET %s: status %d: %s", url, resp.StatusCode, b)
+	}
+	var result map[string]any
+	if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
+		t.Fatalf("decode: %v", err)
+	}
+	return result
+}
+
+func getBody(t *testing.T, url string) ([]byte, int) {
+	t.Helper()
+	resp, err := http.Get(url)
+	if err != nil {
+		t.Fatalf("GET %s: %v", url, err)
+	}
+	defer resp.Body.Close()
+	b, _ := io.ReadAll(resp.Body)
+	return b, resp.StatusCode
+}
+
+func getString(t *testing.T, url string) string {
+	t.Helper()
+	b, status := getBody(t, url)
+	if status != http.StatusOK {
+		t.Fatalf("GET %s: status %d: %s", url, status, b)
+	}
+	return string(b)
+}
+
+func assertStatus(t *testing.T, url string, wantStatus int) {
+	t.Helper()
+	resp, err := http.Get(url)
+	if err != nil {
+		t.Fatalf("GET %s: %v", url, err)
+	}
+	resp.Body.Close()
+	if resp.StatusCode != wantStatus {
+		t.Errorf("GET %s: got %d, want %d", url, resp.StatusCode, wantStatus)
+	}
+}
+
+func deleteRequest(t *testing.T, url string) int {
+	t.Helper()
+	req, _ := http.NewRequest(http.MethodDelete, url, nil)
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatalf("DELETE %s: %v", url, err)
+	}
+	resp.Body.Close()
+	return resp.StatusCode
+}
+
+func mustFormat(format string, args ...any) string {
+	return fmt.Sprintf(format, args...)
+}