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/adapters/data-generators/src/lib.rs

@@ -0,0 +1,59 @@
+use chrono::Utc;
+use chrono_tz::Tz;
+use domain::{DataSource, DataSourceConfig, DataSourcePort, Value};
+use std::collections::BTreeMap;
+
+#[derive(Default)]
+pub struct ClockGenerator;
+
+impl ClockGenerator {
+    pub fn new() -> Self {
+        Self
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum GeneratorError {
+    #[error("wrong config type for generator")]
+    WrongConfig,
+}
+
+impl DataSourcePort for ClockGenerator {
+    type Error = GeneratorError;
+
+    async fn poll(&self, source: &DataSource) -> Result<Value, Self::Error> {
+        let (fmt, tz_name) = match &source.config {
+            DataSourceConfig::Clock { format, timezone } => (format.as_str(), timezone.as_str()),
+            _ => ("%H:%M:%S", "UTC"),
+        };
+        let tz: Tz = tz_name.parse().unwrap_or(chrono_tz::UTC);
+        let now = Utc::now().with_timezone(&tz);
+        let formatted = now.format(fmt).to_string();
+        let mut map = BTreeMap::new();
+        map.insert("time".into(), Value::String(formatted));
+        Ok(Value::Object(map))
+    }
+}
+
+#[derive(Default)]
+pub struct StaticTextGenerator;
+
+impl StaticTextGenerator {
+    pub fn new() -> Self {
+        Self
+    }
+}
+
+impl DataSourcePort for StaticTextGenerator {
+    type Error = GeneratorError;
+
+    async fn poll(&self, source: &DataSource) -> Result<Value, Self::Error> {
+        let text = match &source.config {
+            DataSourceConfig::StaticText { text } => text.clone(),
+            _ => String::new(),
+        };
+        let mut map = BTreeMap::new();
+        map.insert("text".into(), Value::String(text));
+        Ok(Value::Object(map))
+    }
+}