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

internal/cache/redis.go

@@ -0,0 +1,105 @@
+package cache
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/redis/go-redis/v9"
+)
+
+type Redis struct {
+	client *redis.Client
+}
+
+func NewRedis(url string) (*Redis, error) {
+	opts, err := redis.ParseURL(url)
+	if err != nil {
+		return nil, fmt.Errorf("parse redis url: %w", err)
+	}
+
+	client := redis.NewClient(opts)
+
+	if err := client.Ping(context.Background()).Err(); err != nil {
+		return nil, fmt.Errorf("ping redis: %w", err)
+	}
+
+	return &Redis{client: client}, nil
+}
+
+func (r *Redis) Close() error {
+	return r.client.Close()
+}
+
+func (r *Redis) SetTTL(ctx context.Context, remote, path string, ttl time.Duration) error {
+	key := fmt.Sprintf("ttl:%s:%s", remote, path)
+	return r.client.Set(ctx, key, "1", ttl).Err()
+}
+
+func (r *Redis) CheckTTL(ctx context.Context, remote, path string) (bool, error) {
+	key := fmt.Sprintf("ttl:%s:%s", remote, path)
+	exists, err := r.client.Exists(ctx, key).Result()
+	if err != nil {
+		return false, err
+	}
+	return exists > 0, nil
+}
+
+func (r *Redis) AcquireLock(ctx context.Context, remote, path string, ttl time.Duration) (bool, error) {
+	key := fmt.Sprintf("lock:%s:%s", remote, path)
+	ok, err := r.client.SetNX(ctx, key, "1", ttl).Result()
+	return ok, err
+}
+
+func (r *Redis) ReleaseLock(ctx context.Context, remote, path string) error {
+	key := fmt.Sprintf("lock:%s:%s", remote, path)
+	return r.client.Del(ctx, key).Err()
+}
+
+func (r *Redis) SetETag(ctx context.Context, remote, path, etag string, ttl time.Duration) error {
+	key := fmt.Sprintf("etag:%s:%s", remote, path)
+	return r.client.Set(ctx, key, etag, ttl).Err()
+}
+
+func (r *Redis) GetETag(ctx context.Context, remote, path string) (string, error) {
+	key := fmt.Sprintf("etag:%s:%s", remote, path)
+	val, err := r.client.Get(ctx, key).Result()
+	if err == redis.Nil {
+		return "", nil
+	}
+	return val, err
+}
+
+func (r *Redis) IncrCircuitFailure(ctx context.Context, remote string, cooldown time.Duration) (int64, error) {
+	key := fmt.Sprintf("circuit:%s", remote)
+	pipe := r.client.Pipeline()
+	incr := pipe.Incr(ctx, key)
+	pipe.Expire(ctx, key, cooldown)
+	_, err := pipe.Exec(ctx)
+	if err != nil {
+		return 0, err
+	}
+	return incr.Val(), nil
+}
+
+func (r *Redis) ResetCircuit(ctx context.Context, remote string) error {
+	key := fmt.Sprintf("circuit:%s", remote)
+	return r.client.Del(ctx, key).Err()
+}
+
+func (r *Redis) GetCircuitFailures(ctx context.Context, remote string) (int64, error) {
+	key := fmt.Sprintf("circuit:%s", remote)
+	val, err := r.client.Get(ctx, key).Int64()
+	if err == redis.Nil {
+		return 0, nil
+	}
+	return val, err
+}
+
+func (r *Redis) FlushRemote(ctx context.Context, remote string) error {
+	iter := r.client.Scan(ctx, 0, fmt.Sprintf("*:%s:*", remote), 100).Iterator()
+	for iter.Next(ctx) {
+		r.client.Del(ctx, iter.Val())
+	}
+	return iter.Err()
+}