Add config validation and dashboard

Add YAML config loading with validation, env overrides for secrets, and
a web dashboard exposing health, stats, and recent events.

dedup.v

@@ -0,0 +1,129 @@
+module main
+
+import time
+import sources
+
+pub struct DedupEntry {
+pub mut:
+	last_seen time.Time
+	count     int
+}
+
+pub struct Dedup {
+pub mut:
+	enabled        bool
+	ttl_seconds    int
+	max_per_minute int
+	max_per_source int
+	cache          map[string]DedupEntry
+	topic_history  map[string][]time.Time
+	source_history map[string][]time.Time
+}
+
+pub fn new_dedup(cfg DedupConfig) Dedup {
+	return Dedup{
+		enabled:        cfg.enabled
+		ttl_seconds:    cfg.ttl_seconds
+		max_per_minute: cfg.rate_limit.max_per_minute
+		max_per_source: cfg.rate_limit.max_per_source
+		cache:          map[string]DedupEntry{}
+		topic_history:  map[string][]time.Time{}
+		source_history: map[string][]time.Time{}
+	}
+}
+
+fn simple_hash(s string) u64 {
+	mut h := u64(14695981039346656037)
+	for c in s.bytes() {
+		h ^= u64(c)
+		h *= u64(1099511628211)
+	}
+	return h
+}
+
+fn dedup_key(event sources.Event) string {
+	h := simple_hash(event.message)
+	return '${event.source}:${event.name}:${event.topic}:${h}'
+}
+
+fn (mut d Dedup) cleanup(now time.Time) {
+	now_unix := now.unix()
+	for key, entry in d.cache {
+		if now_unix - entry.last_seen.unix() > d.ttl_seconds {
+			d.cache.delete(key)
+		}
+	}
+	for topic, times in d.topic_history {
+		mut kept := []time.Time{}
+		for t in times {
+			if now_unix - t.unix() <= 60 {
+				kept << t
+			}
+		}
+		if kept.len == 0 {
+			d.topic_history.delete(topic)
+		} else {
+			d.topic_history[topic] = kept
+		}
+	}
+	for source, times in d.source_history {
+		mut kept := []time.Time{}
+		for t in times {
+			if now_unix - t.unix() <= 60 {
+				kept << t
+			}
+		}
+		if kept.len == 0 {
+			d.source_history.delete(source)
+		} else {
+			d.source_history[source] = kept
+		}
+	}
+}
+
+pub fn (mut d Dedup) allow(event sources.Event) bool {
+	if !d.enabled {
+		return true
+	}
+	now := time.now()
+	d.cleanup(now)
+
+	// Rate limit per topic
+	topic_times := d.topic_history[event.topic] or { []time.Time{} }
+	if topic_times.len >= d.max_per_minute && d.max_per_minute > 0 {
+		return false
+	}
+
+	// Rate limit per source
+	source_key := '${event.source}:${event.name}'
+	source_times := d.source_history[source_key] or { []time.Time{} }
+	if source_times.len >= d.max_per_source && d.max_per_source > 0 {
+		return false
+	}
+
+	// Dedup check
+	key := dedup_key(event)
+	entry := d.cache[key] or { DedupEntry{} }
+	if entry.count > 0 {
+		d.cache[key] = DedupEntry{
+			last_seen: now
+			count:     entry.count + 1
+		}
+		return false
+	}
+
+	d.cache[key] = DedupEntry{
+		last_seen: now
+		count:     1
+	}
+
+	mut new_topic_times := topic_times.clone()
+	new_topic_times << now
+	d.topic_history[event.topic] = new_topic_times
+
+	mut new_source_times := source_times.clone()
+	new_source_times << now
+	d.source_history[source_key] = new_source_times
+
+	return true
+}