safety: pass current task descr to render_step (Phase 10 C3)

helpers.render_step has supported a (step_n, max_n, descr) signature
since Phase 3 (renderer.lua:246) but safety.norris_step has only ever
called it with two args. Phase 10 lights up the descr slot: when
ctx.norris_tasks is populated (cloud preplanner ran at :norris
launch), the current task text becomes the per-step description so
the user sees `─ step k/N ─ <task>` in real time.

ctx.norris_tasks is nil when:
  - preplan disabled (cfg.norris.preplanner unset)
  - preplan failed (transport / parse / empty)
  - preplan emitted TASKs but already exhausted

In all those cases descr falls through to nil → renderer prints just
the step bar (Phase 3 behavior, no regression).

Regression: 87/87 safety, 31/31 router_model, repl loads. No e2e
visible change yet — ctx.norris_tasks is always nil until C4 wires
the preplan call.

R5 fix: this commit touches safety.lua ONLY (no repl.lua change as
the prior plan implied). Executor cfg resolution + preplan wiring
lands in C4 (next commit).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

safety.lua

@@ -362,7 +362,17 @@ function M.norris_step(ctx, model_cfg, helpers, opts)
     local max_steps = opts.max_steps or 8
     local cfg       = opts.cfg
 
-    helpers.render_step(step_n, max_steps)
+    -- Phase 10 / #89: when the cloud preplanner emitted a TASK list
+    -- at :norris launch, surface the current task as the per-step
+    -- descr so the user sees `─ step k/M ─ <task text>` in real time.
+    -- ctx.norris_tasks is nil when preplan is disabled / failed →
+    -- descr falls through to nil → renderer prints just the step bar
+    -- (existing behavior).
+    local task_descr
+    if ctx.norris_tasks and ctx.norris_tasks.list then
+        task_descr = ctx.norris_tasks.list[ctx.norris_tasks.current]
+    end
+    helpers.render_step(step_n, max_steps, task_descr)
 
     -- (1) one broker round-trip — stream text + collect tool_calls.
     --