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/database/postgres.go

@@ -0,0 +1,126 @@
+package database
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+type DB struct {
+	Pool *pgxpool.Pool
+}
+
+func New(dsn string) (*DB, error) {
+	pool, err := pgxpool.New(context.Background(), dsn)
+	if err != nil {
+		return nil, fmt.Errorf("connect to postgres: %w", err)
+	}
+
+	if err := pool.Ping(context.Background()); err != nil {
+		pool.Close()
+		return nil, fmt.Errorf("ping postgres: %w", err)
+	}
+
+	db := &DB{Pool: pool}
+	if err := db.migrate(); err != nil {
+		pool.Close()
+		return nil, fmt.Errorf("run migrations: %w", err)
+	}
+
+	return db, nil
+}
+
+func (db *DB) Close() {
+	db.Pool.Close()
+}
+
+func (db *DB) migrate() error {
+	ctx := context.Background()
+
+	_, err := db.Pool.Exec(ctx, `
+		CREATE TABLE IF NOT EXISTS remotes (
+			name            TEXT PRIMARY KEY,
+			package_type    TEXT NOT NULL,
+			base_url        TEXT NOT NULL,
+			description     TEXT DEFAULT '',
+			username        TEXT DEFAULT '',
+			password        TEXT DEFAULT '',
+			immutable_ttl   INTEGER DEFAULT 0,
+			mutable_ttl     INTEGER DEFAULT 3600,
+			check_mutable   BOOLEAN DEFAULT TRUE,
+			patterns            TEXT[] DEFAULT '{}',
+			blocklist           TEXT[] DEFAULT '{}',
+			mutable_patterns    TEXT[] DEFAULT '{}',
+			immutable_patterns  TEXT[] DEFAULT '{}',
+			ban_tags_enabled    BOOLEAN DEFAULT FALSE,
+			ban_tags            TEXT[] DEFAULT '{}',
+			quarantine_enabled  BOOLEAN DEFAULT FALSE,
+			quarantine_days     INTEGER DEFAULT 3,
+			stale_on_error      BOOLEAN DEFAULT TRUE,
+			releases_remote     TEXT DEFAULT '',
+			managed_by          TEXT DEFAULT '',
+			created_at      TIMESTAMPTZ DEFAULT NOW(),
+			updated_at      TIMESTAMPTZ DEFAULT NOW()
+		);
+
+		CREATE TABLE IF NOT EXISTS virtuals (
+			name            TEXT PRIMARY KEY,
+			package_type    TEXT NOT NULL,
+			description     TEXT DEFAULT '',
+			members         TEXT[] NOT NULL,
+			managed_by      TEXT DEFAULT '',
+			created_at      TIMESTAMPTZ DEFAULT NOW(),
+			updated_at      TIMESTAMPTZ DEFAULT NOW()
+		);
+
+		CREATE TABLE IF NOT EXISTS blobs (
+			content_hash    TEXT PRIMARY KEY,
+			s3_key          TEXT NOT NULL,
+			size_bytes      BIGINT NOT NULL,
+			content_type    TEXT DEFAULT 'application/octet-stream',
+			created_at      TIMESTAMPTZ DEFAULT NOW()
+		);
+
+		CREATE TABLE IF NOT EXISTS artifacts (
+			id              BIGSERIAL PRIMARY KEY,
+			remote_name     TEXT NOT NULL REFERENCES remotes(name) ON DELETE CASCADE,
+			path            TEXT NOT NULL,
+			content_hash    TEXT NOT NULL REFERENCES blobs(content_hash),
+			upstream_etag   TEXT DEFAULT '',
+			upstream_last_modified TIMESTAMPTZ,
+			first_seen_at   TIMESTAMPTZ DEFAULT NOW(),
+			last_fetched_at TIMESTAMPTZ DEFAULT NOW(),
+			last_accessed_at TIMESTAMPTZ DEFAULT NOW(),
+			fetch_count     BIGINT DEFAULT 1,
+			access_count    BIGINT DEFAULT 1,
+			UNIQUE(remote_name, path)
+		);
+
+		CREATE INDEX IF NOT EXISTS idx_artifacts_remote ON artifacts(remote_name);
+		CREATE INDEX IF NOT EXISTS idx_artifacts_last_accessed ON artifacts(last_accessed_at);
+
+		CREATE TABLE IF NOT EXISTS local_files (
+			id              BIGSERIAL PRIMARY KEY,
+			repo_name       TEXT NOT NULL,
+			file_path       TEXT NOT NULL,
+			content_hash    TEXT NOT NULL REFERENCES blobs(content_hash),
+			created_at      TIMESTAMPTZ DEFAULT NOW(),
+			UNIQUE(repo_name, file_path)
+		);
+
+		CREATE TABLE IF NOT EXISTS access_log (
+			id              BIGSERIAL PRIMARY KEY,
+			remote_name     TEXT NOT NULL,
+			path            TEXT NOT NULL,
+			cache_hit       BOOLEAN NOT NULL,
+			size_bytes      BIGINT DEFAULT 0,
+			upstream_ms     INTEGER DEFAULT 0,
+			client_ip       TEXT DEFAULT '',
+			created_at      TIMESTAMPTZ DEFAULT NOW()
+		);
+
+		CREATE INDEX IF NOT EXISTS idx_access_log_remote_time ON access_log(remote_name, created_at);
+	`)
+	return err
+}