docs(TASK-021): fix task-queue example IDs + document dispatch/collect/failure semantics

- prompts.rs DEFAULT_SPAWN_INSTRUCTIONS: example IDs task_1/task_2 -> "1"/"2"
  (real numeric-string IDs; old format silently produced dep_error + unblocked
  task), plus task-queue rules: root tasks with agent are never auto-dispatched,
  task_complete is what dispatches dependents, auto-dispatched agents must be
  collected, failed tasks permanently block dependents.
- architect config: optional task-queue mirroring guidance for parallel mode
  (disk task files stay the durable store; queue is in-memory).
- sisyphus config: short note on encoding dependency-shaped bursts as
  agent__task_create chains; todos remain the tracking source of truth.

assets/agents/sisyphus/config.yaml

@@ -234,6 +234,11 @@ instructions: |
 
   Never artificially cap at a small number. If there are 10 distinct things to find, spawn 10 agents. The system limit is the only ceiling that matters.
 
+  For dependency-shaped bursts (explore → code → verify), `agent__task_create` chains MAY encode the
+  ordering — dependents with `agent`+`prompt` auto-dispatch when `agent__task_complete` unblocks them.
+  Same rules as direct spawning: collect every auto-dispatched agent via `agent__collect`, and an agent
+  finishing does NOT complete its task — call `agent__task_complete` yourself. Todos remain the tracking source of truth.
+
   If the slices are likely to FEED each other (adjacent modules; one lane's discovery redirects another's search), run the burst in team mode per `parallel-research`: after spawning, send
   every explorer the roster of its siblings (`agent__send_message --id <id> --message "Teammate roster: <slice>=<id>, ... Message a teammate directly when you find a fact in THEIR slice;
   check your inbox after each search round and before finalizing."`) so cross-slice facts move directly between lanes instead of waiting for your synthesis. Never do this with reviewer