initial commit: Artifacto v0.1

Self-hosted HTML artifact publisher. Single Go binary, SQLite metadata,
HTML on disk. Features: password-protected artifacts, per-artifact expiration,
admin dashboard with view metrics (privacy-preserving daily-salt visitor hash,
sparklines, 30-day SVG chart, top referrers), rate-limited unlock endpoint.

Packaged as a Docker image (two-stage, CGO_ENABLED=0, pure-Go SQLite).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/server/ratelimit.go

@@ -0,0 +1,55 @@
+package server
+
+import (
+	"sync"
+	"time"
+)
+
+// Simple token bucket keyed by arbitrary string. Thread-safe.
+type bucket struct {
+	tokens  float64
+	lastRef time.Time
+}
+
+type RateLimiter struct {
+	mu       sync.Mutex
+	buckets  map[string]*bucket
+	capacity float64
+	refill   float64 // tokens per second
+}
+
+// NewRateLimiter: e.g. capacity=5, per=10min → 5 tokens, refilled at 5/600 tokens/sec.
+func NewRateLimiter(capacity int, per time.Duration) *RateLimiter {
+	return &RateLimiter{
+		buckets:  map[string]*bucket{},
+		capacity: float64(capacity),
+		refill:   float64(capacity) / per.Seconds(),
+	}
+}
+
+// Allow returns true if the key has a token to spend.
+func (l *RateLimiter) Allow(key string) bool {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	b, ok := l.buckets[key]
+	now := time.Now()
+	if !ok {
+		b = &bucket{tokens: l.capacity, lastRef: now}
+		l.buckets[key] = b
+	}
+	elapsed := now.Sub(b.lastRef).Seconds()
+	b.tokens = minF(l.capacity, b.tokens+elapsed*l.refill)
+	b.lastRef = now
+	if b.tokens >= 1 {
+		b.tokens--
+		return true
+	}
+	return false
+}
+
+func minF(a, b float64) float64 {
+	if a < b {
+		return a
+	}
+	return b
+}