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.

webhook.v

@@ -0,0 +1,47 @@
+module main
+
+// WebhookRoute maps a webhook path to its source type and index for O(1) dispatch.
+pub enum SourceKind {
+	gitea
+	uptime_kuma
+	cron
+	generic
+}
+
+pub struct WebhookRoute {
+	kind  SourceKind
+	index int // index in the config's source array
+}
+
+// build_webhook_routes constructs a map of webhook_path → WebhookRoute
+// for O(1) dispatch instead of scanning all sources on every request.
+pub fn build_webhook_routes(cfg Config) map[string]WebhookRoute {
+	mut routes := map[string]WebhookRoute{}
+
+	for i, src in cfg.sources.gitea {
+		routes[src.webhook_path] = WebhookRoute{
+			kind:  .gitea
+			index: i
+		}
+	}
+	for i, src in cfg.sources.uptime_kuma {
+		routes[src.webhook_path] = WebhookRoute{
+			kind:  .uptime_kuma
+			index: i
+		}
+	}
+	for i, src in cfg.sources.cron {
+		routes[src.webhook_path] = WebhookRoute{
+			kind:  .cron
+			index: i
+		}
+	}
+	for i, src in cfg.sources.generic {
+		routes[src.webhook_path] = WebhookRoute{
+			kind:  .generic
+			index: i
+		}
+	}
+
+	return routes
+}