assets: bundle short excited move (enthusiastic1) for the emotion button code + CI guard

Author: RemiFabre

src/reachy_mini/assets/handshake_moves/README.md

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+# Handshake emotion move
+
+`excited.json` (+ `excited.wav`) is the single fixed "excited" move played by
+the torque-ON emotion antenna-button code (left, right, left, right external;
+see `daemon/backend/secret_handshake.py` and the design spec
+`docs/superpowers/specs/2026-07-07-antenna-button-handshakes-design.md`).
+
+It is bundled here so it ships in the wheel and works offline (no network
+fetch at play time). Loaded via `RecordedMove` and played with a short
+`initial_goto_duration` so the robot eases into the move's start pose.
+
+Provenance: `enthusiastic1` from `pollen-robotics/reachy-mini-emotions-library`
+(HF dataset, snapshot 152e84b8f46b88c4b52dd34bbef6975637366177), ~2.73 s,
+"A movement to celebrate incredible news." Renamed to `excited` for its role
+here. To swap the move, drop in another library move's JSON (+ optional WAV)
+under this name.

src/reachy_mini/assets/handshake_moves/excited.json

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+"""The bundled handshake emotion move must ship and load as a RecordedMove.
+
+Guards the asset the torque-ON emotion button code plays (see
+docs/superpowers/specs/2026-07-07-antenna-button-handshakes-design.md). If the
+file is missing or malformed the daemon skips the emotion gracefully, but it
+should ship valid, so this is a hard check.
+"""
+
+import json
+from importlib import resources
+
+from reachy_mini.motion.recorded_move import RecordedMove
+
+
+def test_bundled_excited_move_loads_and_is_short():
+    base = resources.files("reachy_mini") / "assets" / "handshake_moves"
+    move_file = base / "excited.json"
+    assert move_file.is_file(), "excited.json must ship under assets/handshake_moves"
+
+    data = json.loads(move_file.read_text())
+    move = RecordedMove(data, None)
+
+    assert move.duration > 0.0
+    # A fixed SHORT excited move (some library moves are very long).
+    assert move.duration < 6.0
+    # The move can be sampled across its span without raising (evaluate()
+    # rejects t at/after the final timestamp by design, so stop just short).
+    move.evaluate(0.0)
+    move.evaluate(move.duration * 0.99)