extract shared transcript parser and similarity matching helpers

- New agents/transcript.rs: shared JSONL parsing for enrich, fact_mine,
  and knowledge (was 3 separate implementations, ~150 lines duplicated)
- New best_match() and section_children() helpers in neuro/rewrite.rs
  (was duplicated find-best-by-similarity loop + section collection)
- Net -153 lines

poc-memory/src/agents/enrich.rs

@@ -72,53 +72,11 @@ pub fn is_transcript_mined_with_keys(mined: &HashSet<String>, path: &str) -> boo
 /// Extract user/assistant messages with line numbers from a JSONL transcript.
 /// (line_number, role, text, timestamp)
 pub fn extract_conversation(jsonl_path: &str) -> Result<Vec<(usize, String, String, String)>, String> {
-    let content = fs::read_to_string(jsonl_path)
-        .map_err(|e| format!("read {}: {}", jsonl_path, e))?;
-
-    let mut messages = Vec::new();
-    for (i, line) in content.lines().enumerate() {
-        let obj: serde_json::Value = match serde_json::from_str(line) {
-            Ok(v) => v,
-            Err(_) => continue,
-        };
-
-        let msg_type = obj.get("type").and_then(|v| v.as_str()).unwrap_or("");
-        if msg_type != "user" && msg_type != "assistant" { continue; }
-
-        let timestamp = obj.get("timestamp")
-            .and_then(|v| v.as_str())
-            .unwrap_or("")
-            .to_string();
-
-        let msg = obj.get("message").unwrap_or(&obj);
-        let content = msg.get("content");
-
-        let text = match content {
-            Some(serde_json::Value::String(s)) => s.clone(),
-            Some(serde_json::Value::Array(arr)) => {
-                arr.iter()
-                    .filter_map(|c| {
-                        // Only extract text blocks; skip tool_use, tool_result, thinking, etc.
-                        let is_text = c.get("type").and_then(|v| v.as_str()) == Some("text");
-                        if is_text {
-                            c.get("text").and_then(|v| v.as_str()).map(|s| s.to_string())
-                        } else {
-                            c.as_str().map(|s| s.to_string())
-                        }
-                    })
-                    .collect::<Vec<_>>()
-                    .join("\n")
-            }
-            _ => continue,
-        };
-
-        let text = text.trim().to_string();
-        if text.is_empty() { continue; }
-
-        messages.push((i + 1, msg_type.to_string(), text, timestamp));
-    }
-
-    Ok(messages)
+    let path = std::path::Path::new(jsonl_path);
+    let messages = super::transcript::parse_transcript(path)?;
+    Ok(messages.into_iter()
+        .map(|m| (m.line, m.role, m.text, m.timestamp))
+        .collect())
 }
 
 pub const COMPACTION_MARKER: &str = "This session is being continued from a previous conversation that ran out of context";