webhook through event system, extract data-generators adapter

webhook route now emits WebhookDataReceived event instead of directly
mutating DataProjection and broadcasting. event_handler applies data
and pushes incremental DataUpdate.

clock/static_text generators extracted to data-generators crate behind
DataSourcePort. chrono removed from bootstrap. polling adapters grouped
into Adapters struct.

crates/domain/src/events/mod.rs

@@ -1,17 +1,43 @@
 use crate::entities::{DataSourceId, LayoutPresetId, WidgetId};
-use crate::value_objects::{Layout, ThemeConfig};
+use crate::value_objects::{Layout, ThemeConfig, Value};
 
 #[derive(Debug, Clone)]
 pub enum DomainEvent {
-    WidgetCreated { id: WidgetId },
-    WidgetUpdated { id: WidgetId },
-    WidgetDeleted { id: WidgetId },
-    DataSourceAdded { id: DataSourceId },
-    DataSourceUpdated { id: DataSourceId },
-    DataSourceRemoved { id: DataSourceId },
-    LayoutChanged { layout: Layout },
-    ThemeChanged { theme: ThemeConfig },
-    LayoutPresetSaved { id: LayoutPresetId },
-    LayoutPresetLoaded { id: LayoutPresetId },
-    LayoutPresetDeleted { id: LayoutPresetId },
+    WidgetCreated {
+        id: WidgetId,
+    },
+    WidgetUpdated {
+        id: WidgetId,
+    },
+    WidgetDeleted {
+        id: WidgetId,
+    },
+    DataSourceAdded {
+        id: DataSourceId,
+    },
+    DataSourceUpdated {
+        id: DataSourceId,
+    },
+    DataSourceRemoved {
+        id: DataSourceId,
+    },
+    LayoutChanged {
+        layout: Layout,
+    },
+    ThemeChanged {
+        theme: ThemeConfig,
+    },
+    LayoutPresetSaved {
+        id: LayoutPresetId,
+    },
+    LayoutPresetLoaded {
+        id: LayoutPresetId,
+    },
+    LayoutPresetDeleted {
+        id: LayoutPresetId,
+    },
+    WebhookDataReceived {
+        source_id: DataSourceId,
+        data: Value,
+    },
 }