Portable Python env + 360° LiDAR ablation flag

Two small features.

(1) Portable interpreter
* `tools/setup_env.sh` exports HERDING_PYTHON (default points to the
  project's conda env; override in your shell to retarget).
* Both `controllers/*/runtime.ini` files now use Webots' env-var
  expansion: `COMMAND = $(HERDING_PYTHON)` so the Webots-launched
  controllers pick up the same interpreter as the bash scripts.
* `tools/run_webots.sh`, `tools/webots_sweep{,_gt}.sh` and
  `tools/calibrate_mecanum.sh` all source `setup_env.sh` at the top
  instead of hard-coding `/home/jalf/miniconda3/envs/tir/bin`.
The hard-coded conda path is now exactly one line in `setup_env.sh`'s
fallback default — a single place to edit on a new machine, or
override-once via `export HERDING_PYTHON=...`.

(2) 360° LiDAR FOV ablation
* New `LIDAR_WEBOTS_360` preset matches the existing
  `protos/ShepherdDog360.proto` (360 rays / 2π FOV / 15 m range).
* `tools/run_webots.sh` reads `HERDING_LIDAR=140|360` and swaps the
  diff-drive proto accordingly (mecanum keeps 140° — the
  ShepherdDogMecanum proto has its own LiDAR section). The variant
  is written into `herding_runtime.cfg` so the controller can read
  it even when Webots strips env vars.
* `controllers/shepherd_dog/shepherd_dog.py` picks the matching
  `lidar_cfg` (`HERDING_WEBOTS.lidar` for 140°, `LIDAR_WEBOTS_360`
  otherwise) and feeds it to `detections_from_scan` so the
  perception pipeline interprets ray angles + max range correctly.

Smoke test: `HERDING_LIDAR=360 tools/run_webots.sh 5 strombom
differential field` launches with `ShepherdDog360.proto`, the
controller logs the new mode/drive/world line, and the dog is
penning sheep through 360° perception (4/5 at step 19200 before I
killed the test). No retraining required because the gym already
trains under `LIDAR_FULL` (360° preset).

126 pytest cases still pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tools/run_webots.sh

@@ -33,6 +33,12 @@
 #   WEBOTS_EXTRA_ARGS="--stdout --stderr" WEBOTS_HEADLESS=1 tools/run_webots.sh 10 rl
 
 set -e
+
+# Make sure HERDING_PYTHON is resolved and on PATH so Webots inherits
+# the right interpreter (controllers/{shepherd_dog,sheep}/runtime.ini
+# both read $HERDING_PYTHON via env-var expansion).
+source "$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )/setup_env.sh"
+
 N=${1:-10}
 MODE=${2:-bc}
 DRIVE=${3:-differential}
@@ -84,12 +90,31 @@ fi
 
 cp "$SRC" "$DST"
 
-# Swap robot proto based on drive mode.
-# Base worlds reference ShepherdDog (diff-drive). For mecanum we swap in
-# ShepherdDogMecanum and inject mecanum contact properties.
+# LiDAR FOV variant: HERDING_LIDAR=140 (default) or 360 (ablation).
+# 360° is only supported for differential drive; the mecanum proto
+# always uses the 140° sensor matching ShepherdDog.proto.
+LIDAR_VARIANT="${HERDING_LIDAR:-140}"
+if [[ "$LIDAR_VARIANT" != "140" && "$LIDAR_VARIANT" != "360" ]]; then
+    echo "HERDING_LIDAR must be 140 or 360, got '$LIDAR_VARIANT'" >&2; exit 1
+fi
+if [[ "$LIDAR_VARIANT" == "360" && "$DRIVE" == "mecanum" ]]; then
+    echo "[run_webots] HERDING_LIDAR=360 not available for mecanum drive — falling back to 140." >&2
+    LIDAR_VARIANT="140"
+fi
+export HERDING_LIDAR="$LIDAR_VARIANT"
+
+# Swap robot proto based on drive mode + LiDAR variant.
+# Base worlds reference ShepherdDog (diff-drive 140°). For mecanum we
+# swap in ShepherdDogMecanum; for the 360° ablation we swap in
+# ShepherdDog360.
 if [[ "$DRIVE" == "mecanum" ]]; then
     sed -i 's|"../protos/ShepherdDog.proto"|"../protos/ShepherdDogMecanum.proto"|' "$DST"
     sed -i 's|^ShepherdDog {|ShepherdDogMecanum {|' "$DST"
+elif [[ "$LIDAR_VARIANT" == "360" ]]; then
+    sed -i 's|"../protos/ShepherdDog.proto"|"../protos/ShepherdDog360.proto"|' "$DST"
+    sed -i 's|^ShepherdDog {|ShepherdDog360 {|' "$DST"
+fi
+if [[ "$DRIVE" == "mecanum" ]]; then
     # Inject mecanum roller contact properties. The proto's rollers are
     # split into two contact materials so that we can keep the friction
     # axes oriented along each roller's free-spin direction — but with
@@ -152,6 +177,7 @@ HERDING_MODE=$MODE
 HERDING_POLICY_DIR=$RESOLVED_POLICY_DIR
 HERDING_DRIVE=$DRIVE
 HERDING_WORLD=$WORLD
+HERDING_LIDAR=$LIDAR_VARIANT
 HERDING_USE_GT=${HERDING_USE_GT:-0}
 EOF
 
@@ -159,6 +185,7 @@ export HERDING_MODE="$MODE"
 export HERDING_POLICY_DIR="$RESOLVED_POLICY_DIR"
 export HERDING_DRIVE="$DRIVE"
 export HERDING_WORLD="$WORLD"
+export HERDING_LIDAR="$LIDAR_VARIANT"
 
 # The controller writes this sentinel when all GT sheep are penned. We
 # poll for it and kill Webots so the run finishes cleanly instead of