Add lab restream pipeline with pirate_drift logo and lib/env.sh.

Encode-once/fanout scripts, HLS output, and single overloadable env source.
Commits assets/pirate_drift.png as default watermark for cluster runs.

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/common.sh

@@ -0,0 +1,98 @@
+#!/usr/bin/env bash
+# Shared bootstrap: ROOT, env defaults, encoding presets, pipe helpers.
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+export ROOT
+
+# shellcheck disable=SC1091
+source "${ROOT}/lib/logging.sh"
+# shellcheck disable=SC1091
+source "${ROOT}/lib/env.sh"
+
+apply_encoding_preset() {
+  case "${OUTPUT_PRESET}" in
+    720p)
+      WIDTH=1280
+      HEIGHT=720
+      FASTNESS=veryfast
+      BV=2500k
+      BUFSIZE=5000k
+      ;;
+    1080p|*)
+      WIDTH=1920
+      HEIGHT=1080
+      FASTNESS=faster
+      BV=5000k
+      BUFSIZE=10000k
+      ;;
+  esac
+  export WIDTH HEIGHT FASTNESS BV BUFSIZE
+  RES="${WIDTH}x${HEIGHT}"
+  PROFILE=high
+  KEYFRAMES_INTL="${FPS}"
+  GOP_INTL=$((KEYFRAMES_INTL * 2))
+  PIX_FMT="-pix_fmt yuv420p"
+  PRESET="-preset ${FASTNESS} -tune zerolatency -profile:v ${PROFILE} ${PIX_FMT} -x264-params keyint=${KEYFRAMES_INTL}:min-keyint=${KEYFRAMES_INTL} -g ${GOP_INTL} -flags +global_header"
+  BITRATE="-b:v ${BV} -maxrate ${BV} -minrate ${BV}"
+  VCODEC="-c:v libx264"
+  ACODEC="-c:a aac -b:a 128k"
+  export RES PROFILE PRESET BITRATE VCODEC ACODEC
+}
+
+apply_encoding_preset
+
+FFMPEG_TS_FLAGS=(
+  -fflags +genpts+igndts
+  -avoid_negative_ts make_zero
+  -sn
+  -movflags +faststart
+)
+
+read_rate_flag() {
+  if [[ "${NEAR_REALTIME}" == "1" ]]; then
+    RE_FLAG=(-re)
+  else
+    RE_FLAG=()
+  fi
+}
+
+ensure_storage() {
+  mkdir -p "${STORAGE_DIR}" "${RUN_DIR}"
+}
+
+ensure_pipe() {
+  if [[ ! -p "${PIPE_PATH}" ]]; then
+    mkfifo "${PIPE_PATH}"
+    if command -v perl >/dev/null 2>&1; then
+      perl -MFcntl -e 'fcntl(STDIN, 1031, shift) or die $!' "${PIPE_FIFO_SIZE}" <> "${PIPE_PATH}" || true
+    fi
+  fi
+  exec 7<> "${PIPE_PATH}"
+}
+
+remove_pipe() {
+  exec 7>&- 7<&- 2>/dev/null || true
+  rm -f "${PIPE_PATH}" 2>/dev/null || true
+}
+
+next_record_path() {
+  local counter=0 name
+  ensure_storage
+  while true; do
+    name="$(printf "video%04d.%s" "${counter}" "${RECORD_FORMAT}")"
+    if [[ ! -f "${STORAGE_DIR}/${name}" ]]; then
+      echo "${STORAGE_DIR}/${name}"
+      return
+    fi
+    counter=$((counter + 1))
+  done
+}
+
+require_cmd() {
+  command -v "$1" >/dev/null 2>&1 || die "required command not found: $1"
+}
+
+require_logo() {
+  [[ -f "${LOGO_PATH}" ]] || die "logo not found at ${LOGO_PATH} (expected ${ROOT}/assets/pirate_drift.png)"
+}