enrich: set created_at from event timestamp, not mining time

Experience-mined journal entries were all getting created_at = now(),
causing them to sort by mining time instead of when the event actually
happened. Parse the conversation timestamp and set created_at to the
event time so journal-tail shows correct chronological order.

src/enrich.rs

@@ -19,6 +19,21 @@ use std::hash::{Hash, Hasher};
 
 use crate::store::StoreView;
 
+/// Parse a timestamp string like "2026-03-05T19:56" to unix epoch seconds.
+fn parse_timestamp_to_epoch(ts: &str) -> Option<i64> {
+    use chrono::{Local, NaiveDateTime, TimeZone};
+    // Try common formats
+    let formats = ["%Y-%m-%dT%H:%M:%S", "%Y-%m-%dT%H:%M", "%Y-%m-%d %H:%M:%S", "%Y-%m-%d %H:%M"];
+    for fmt in &formats {
+        if let Ok(ndt) = NaiveDateTime::parse_from_str(ts, fmt) {
+            if let Some(dt) = Local.from_local_datetime(&ndt).earliest() {
+                return Some(dt.timestamp());
+            }
+        }
+    }
+    None
+}
+
 /// Compute the store dedup key for a transcript file.
 /// This is the same key experience_mine uses to mark a transcript as mined.
 pub fn transcript_dedup_key(path: &str) -> Result<String, String> {
@@ -353,11 +368,16 @@ pub fn experience_mine(
             continue;
         }
 
-        // Write to store
+        // Write to store — use event timestamp, not mining time
         let mut node = new_node(&key, &full_content);
         node.node_type = store::NodeType::EpisodicSession;
         node.category = store::Category::Observation;
         node.provenance = store::Provenance::AgentExperienceMine;
+        if !ts.is_empty() {
+            if let Some(epoch) = parse_timestamp_to_epoch(ts) {
+                node.created_at = epoch;
+            }
+        }
         let _ = store.upsert_node(node);
         count += 1;