fix(kanban): tell workers not to use clarify; route to kanban_block instead (#32167)

Kanban workers run headless — no live user is on the other side of `clarify`,
so the call times out (~120s default) and the task sits silently in `running`
with no signal to the operator that input is needed. Reporter observed a real
incident where a worker asked 'promote to production, or check staging first?'
via clarify, the call timed out, the agent hallucinated a fallback, and the
task sat 'running' for hours.

Fix: explicit 'do not call clarify' bullet in two surfaces every kanban worker
sees —

- `agent/prompt_builder.py` KANBAN_GUIDANCE `## Do NOT` section (auto-injected
  into every dispatcher-spawned worker run).
- `skills/devops/kanban-worker/SKILL.md` `## Do NOT` section (the bundled
  worker skill).

Both point at the right pattern: `kanban_comment` (context) + `kanban_block`
(decision needed) — the task surfaces on the board as blocked, the operator
sees it, unblocks with their answer in a comment, and the worker respawns
with the thread.

Co-authored-by: kweiner <17778+kweiner@users.noreply.github.com>

skills/devops/kanban-worker/SKILL.md

@@ -167,6 +167,7 @@ You can configure the gateway to receive cross-profile Kanban task notifications
 ## Do NOT
 
 - Call `delegate_task` as a substitute for `kanban_create`. `delegate_task` is for short reasoning subtasks inside YOUR run; `kanban_create` is for cross-agent handoffs that outlive one API loop.
+- Call `clarify` to ask the human a question. You are running headless — there is no live user to answer. The call will time out (default ~120s) and the task will sit silently in `running` with no signal that it needs input. Use `kanban_comment` (context) + `kanban_block(reason=...)` (decision needed) instead — the task surfaces on the board as blocked, the operator sees it, unblocks with their answer in a comment, and you respawn with the thread.
 - Modify files outside `$HERMES_KANBAN_WORKSPACE` unless the task body says to.
 - Create follow-up tasks assigned to yourself — assign to the right specialist.
 - Complete a task you didn't actually finish. Block it instead.