feat(annotations): enforce imperative verb-first subtask phrasing

Rewrite module_1_subtasks prompt to produce short imperative commands
("pick up the orange") instead of third-person narration ("the robot
arm moves to the orange"). Drops the verbose "how, not what" rule and
adds a good/bad few-shot table.

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

src/lerobot/annotations/steerable_pipeline/prompts/module_1_subtasks.txt

@@ -6,15 +6,18 @@ You are shown the entire demonstration as a single video. Watch the
 whole clip, then segment it into a list of consecutive atomic subtasks
 the robot performs.
 
-Authoring rules — based on Hi Robot (Shi 2025) atom granularity and
-Pi0.7 (Physical Intelligence 2025) "how, not what" detail:
+Authoring rules — based on Hi Robot (Shi 2025) atom granularity:
 
 - Each subtask is one atomic skill the low-level policy can execute,
-  e.g. "pick up one piece of lettuce", "place the bowl into the box",
-  "move the right arm to the left".
-- Capture HOW the subtask is performed, not only WHAT — e.g. prefer
-  "grasp the handle of the sponge with the left hand" to "pick up the
-  sponge".
+  e.g. "pick up the orange", "place the bowl into the box".
+- Write each subtask as an IMPERATIVE COMMAND to the robot, starting
+  with a verb: move, reach, pick up, grasp, place, put, push, pull,
+  open, close, turn, press, lift, insert, pour...
+- NEVER use third person. Never write "the robot", "the arm", "the
+  gripper moves", "it picks up". Command the robot, do not describe it.
+- Keep it SHORT — 3 to 8 words. Add a "how" detail (which hand, which
+  grasp point) ONLY when it is needed to disambiguate.
+- Lower-case, no trailing period.
 - Subtasks are non-overlapping and cover the full episode in order.
   Choose the cut points yourself based on what you see in the video
   (gripper open/close events, contact, regrasps, transitions).
@@ -23,11 +26,22 @@ Pi0.7 (Physical Intelligence 2025) "how, not what" detail:
 - Every subtask's [start_time, end_time] must lie within
   [0.0, {episode_duration}] seconds.
 
+Style examples:
+
+  Good                            Bad (do NOT produce these)
+  "pick up the orange"            "the robot arm moves to the orange"
+  "move to the yellow block"      "the gripper approaches the block"
+  "close gripper to grasp         "close the gripper to grasp the
+   the yellow cube"                yellow cube so it can lift it"
+  "open the toaster oven"         "it opens the toaster oven door"
+  "put the bagel on the           "the white plate now has the bagel
+   white plate"                    placed on it by the arm"
+
 Output strictly valid JSON of shape:
 
   {{
     "subtasks": [
-      {{"text": "<how-not-what>", "start": <float>, "end": <float>}},
+      {{"text": "<short imperative command>", "start": <float>, "end": <float>}},
       ...
     ]
   }}