observation agent rewrite, edit command, daemon fixes

- observation.agent: rewritten to navigate graph and prefer refining
  existing nodes over creating new ones. Identity-framed prompt,
  goals over rules.
- poc-memory edit: opens node in $EDITOR, writes back on save,
  no-op if unchanged
- daemon: remove extra_workers (jobkit tokio migration dropped it),
  remove sequential chaining of same-type agents (in-flight exclusion
  is sufficient)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

poc-memory/src/main.rs

@@ -69,6 +69,11 @@ enum Command {
         /// Node key
         key: Vec<String>,
     },
+    /// Edit a node in $EDITOR
+    Edit {
+        /// Node key
+        key: Vec<String>,
+    },
     /// Show all stored versions of a node
     History {
         /// Show full content for every version
@@ -778,6 +783,7 @@ fn main() {
             => cli::misc::cmd_search(&query, &pipeline, expand, full, debug, fuzzy, content),
         Command::Render { key } => cli::node::cmd_render(&key),
         Command::Write { key } => cli::node::cmd_write(&key),
+        Command::Edit { key } => cli::node::cmd_edit(&key),
         Command::History { full, key } => cli::node::cmd_history(&key, full),
         Command::Tail { n, full } => cli::journal::cmd_tail(n, full),
         Command::Status => cli::misc::cmd_status(),