daemon status: add in-flight tasks, recent completions, and node history command

Show running/pending tasks with elapsed time, progress, and last 3
output lines. Show last 20 completed/failed jobs from daemon log.
Both displayed before the existing grouped task view.

Add 'poc-memory history KEY' command that replays the append-only node
log to show all versions of a key with version number, weight, timestamp,
and content preview. Useful for auditing what modified a node.

src/main.rs

@@ -107,6 +107,7 @@ fn main() {
         "journal-ts-migrate"    => cmd_journal_ts_migrate(),
         "load-context"          => cmd_load_context(&args[2..]),
         "render"                => cmd_render(&args[2..]),
+        "history"               => cmd_history(&args[2..]),
         "write"                 => cmd_write(&args[2..]),
         "import"                => cmd_import(&args[2..]),
         "export"                => cmd_export(&args[2..]),
@@ -1547,6 +1548,57 @@ fn cmd_render(args: &[String]) -> Result<(), String> {
     Ok(())
 }
 
+fn cmd_history(args: &[String]) -> Result<(), String> {
+    if args.is_empty() {
+        return Err("Usage: poc-memory history KEY".into());
+    }
+    let key = args.join(" ");
+
+    // Replay the node log, collecting all versions of this key
+    let path = store::nodes_path();
+    if !path.exists() {
+        return Err("No node log found".into());
+    }
+
+    use std::io::BufReader;
+    let file = std::fs::File::open(&path)
+        .map_err(|e| format!("open {}: {}", path.display(), e))?;
+    let mut reader = BufReader::new(file);
+
+    let mut versions: Vec<store::Node> = Vec::new();
+    while let Ok(msg) = capnp::serialize::read_message(&mut reader, capnp::message::ReaderOptions::new()) {
+        let log = msg.get_root::<poc_memory::memory_capnp::node_log::Reader>()
+            .map_err(|e| format!("read log: {}", e))?;
+        for node_reader in log.get_nodes()
+            .map_err(|e| format!("get nodes: {}", e))? {
+            let node = store::Node::from_capnp(node_reader)?;
+            if node.key == key {
+                versions.push(node);
+            }
+        }
+    }
+
+    if versions.is_empty() {
+        return Err(format!("No history found for '{}'", key));
+    }
+
+    eprintln!("{} versions of '{}':\n", versions.len(), key);
+    for (i, node) in versions.iter().enumerate() {
+        let preview: String = node.content.chars().take(200).collect();
+        let preview = preview.replace('\n', "\\n");
+        eprintln!("  v{} (w={:.3}, {}): {}",
+            node.version, node.weight, node.timestamp, preview);
+    }
+
+    // Show latest full content
+    if let Some(latest) = versions.last() {
+        eprintln!("\n--- Latest content (v{}) ---", latest.version);
+        print!("{}", latest.content);
+    }
+
+    Ok(())
+}
+
 fn cmd_write(args: &[String]) -> Result<(), String> {
     if args.is_empty() {
         return Err("Usage: poc-memory write KEY < content\n\