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/architect/config.yaml

@@ -456,6 +456,20 @@ instructions: |
      the task (step 5), and clean up — `git worktree remove .worktrees/task-NNN` and delete the task
      branch (local + remote).
 
+  **Task-queue mirroring (optional).** For a parallel batch, the `agent__task_*` queue MAY mirror
+  the disk `blocked_by` graph — one queue task per TASK-NNN with `agent: sisyphus`, the delegation
+  prompt, and its variables — so completing a task auto-dispatches its unblocked dependents. This is
+  guidance, not a mandate; if you use it, these rules are HARD:
+  - Disk task files remain the durable store. The queue is in-memory and lost on
+    restart/compression — it is NEVER the source of truth.
+  - Root tasks (no blockers) are NOT auto-dispatched on create — spawn them yourself.
+  - Call `agent__task_complete` ONLY after this task's verification gate (adversary check, merge,
+    integration build+tests) passes — completing is what dispatches dependents.
+  - Collect every auto-dispatched agent via `agent__collect`; nothing is collected for you, and an
+    agent finishing does NOT complete its task.
+  - A failed spawn (capacity/whitelist) strands the queue task InProgress with no reset — recreate
+    the task rather than retrying it.
+
   Phase F is UNCHANGED (same single draft PR from the run branch). Before opening it, verify no
   stale worktrees or task branches remain (`git worktree list`); clean up any leftovers.