updating to match everything in my homelab.

diagrams/notification-architecture.mmd

@@ -0,0 +1,63 @@
+```plaintext
+%% Notification Architecture (ADR-0021)
+%% C4 Component diagram showing notification sources and hub
+
+flowchart LR
+    subgraph sources["📤 Notification Sources"]
+        direction TB
+        ci["🔧 Gitea Actions<br/>CI/CD builds"]
+        alertmanager["🔔 Alertmanager<br/>Prometheus alerts"]
+        gatus["❤️ Gatus<br/>Health monitoring"]
+        flux["🔄 Flux<br/>GitOps events"]
+    end
+
+    subgraph hub["📡 Central Hub"]
+        ntfy["📢 ntfy<br/>Notification Server"]
+    end
+
+    subgraph topics["🏷️ Topics"]
+        direction TB
+        t_ci["gitea-ci"]
+        t_alerts["alertmanager-alerts"]
+        t_gatus["gatus"]
+        t_flux["flux"]
+        t_deploy["deployments"]
+    end
+
+    subgraph consumers["📱 Consumers"]
+        direction TB
+        mobile["📱 ntfy App<br/>(iOS/Android)"]
+        bridge["🌉 ntfy-discord<br/>Bridge"]
+        discord["💬 Discord<br/>Webhooks"]
+    end
+
+    %% Source to hub
+    ci -->|"POST"| ntfy
+    alertmanager -->|"webhook"| ntfy
+    gatus -->|"webhook"| ntfy
+    flux -->|"notification-controller"| ntfy
+
+    %% Hub to topics
+    ntfy --> topics
+
+    %% Topics to consumers
+    t_ci --> mobile
+    t_alerts --> mobile
+    t_gatus --> mobile
+    t_flux --> mobile
+    t_deploy --> mobile
+
+    topics --> bridge
+    bridge --> discord
+
+    classDef source fill:#3498db,color:white
+    classDef hub fill:#e74c3c,color:white
+    classDef topic fill:#9b59b6,color:white
+    classDef consumer fill:#27ae60,color:white
+
+    class ci,alertmanager,gatus,flux source
+    class ntfy hub
+    class t_ci,t_alerts,t_gatus,t_flux,t_deploy topic
+    class mobile,bridge,discord consumer
+
+```