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.

sources/generic.v

@@ -0,0 +1,13 @@
+module sources
+
+pub fn transform_generic(raw string, source GenericSource) ?Event {
+	return Event{
+		source:   'generic'
+		name:     source.name
+		topic:    source.topic
+		priority: source.priority_map['default'] or { 0 }
+		tags:     source.tags.clone()
+		message:  raw
+		raw:      raw
+	}
+}