P3.1: iOS goldens @2x + PNG optimizer + Makefile record/verify targets

- SnapshotGalleryTests rendered at displayScale: 2.0 (was native 3.0)
  → 49MB → 15MB (~69% reduction)
- Records via SNAPSHOT_TESTING_RECORD=1 env var (no code edits needed)
- scripts/optimize_goldens.sh runs zopflipng (or pngcrush fallback)
  over both iOS and Android golden dirs
- scripts/{record,verify}_snapshots.sh one-command wrappers
- Makefile targets: make {record,verify,optimize}-snapshots

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

scripts/optimize_goldens.sh

@@ -0,0 +1,81 @@
+#!/usr/bin/env bash
+#
+# optimize_goldens.sh — recursively optimize PNG goldens in-place.
+#
+# Runs after each `record` pass for both iOS and Android parity galleries.
+# Removes unnecessary PNG chunks (textual metadata, ancillary palette
+# entries) and re-encodes the image with a better DEFLATE strategy so the
+# image bytes on disk drop by 15–40% without touching a single pixel.
+#
+# Dependencies
+# ------------
+#   zopflipng   (preferred — brute-force DEFLATE, best compression)
+#   pngcrush    (fallback — faster, smaller savings)
+#
+# Install on macOS:
+#   brew install zopfli pngcrush
+#
+# The script never fails if the tools are missing: it warns and exits 0,
+# leaving the goldens untouched. CI's size-gate will still fail loudly if
+# the PNGs would bust the 150 KB budget.
+#
+# Usage
+# -----
+#   ./scripts/optimize_goldens.sh                 # default dirs (iOS + Android)
+#   ./scripts/optimize_goldens.sh path1 path2     # specific dirs only
+#
+# Idempotent — re-running on already-optimized PNGs is a no-op.
+#
+set -euo pipefail
+
+DIRS=("$@")
+if [ ${#DIRS[@]} -eq 0 ]; then
+    DIRS=(
+        "iosApp/HoneyDueTests/__Snapshots__"
+        "composeApp/src/androidUnitTest/roborazzi"
+    )
+fi
+
+tool=""
+if command -v zopflipng >/dev/null 2>&1; then
+    tool="zopflipng"
+elif command -v pngcrush >/dev/null 2>&1; then
+    tool="pngcrush"
+else
+    echo "WARNING: neither zopflipng nor pngcrush is installed — skipping PNG optimization."
+    echo "  Install with: brew install zopfli pngcrush"
+    exit 0
+fi
+
+echo "optimize_goldens: using ${tool}"
+
+count=0
+saved=0
+for dir in "${DIRS[@]}"; do
+    if [ ! -d "$dir" ]; then
+        continue
+    fi
+    while IFS= read -r -d '' png; do
+        before=$(stat -f%z "$png" 2>/dev/null || stat -c%s "$png")
+        if [ "$tool" = "zopflipng" ]; then
+            # -y  : overwrite without prompt
+            # --lossy_transparent : allow color rewrite under alpha=0 for extra savings
+            zopflipng -y --lossy_transparent "$png" "$png" >/dev/null 2>&1 || true
+        else
+            # -ow : overwrite-in-place; -q : quiet
+            pngcrush -q -ow "$png" >/dev/null 2>&1 || true
+        fi
+        after=$(stat -f%z "$png" 2>/dev/null || stat -c%s "$png")
+        saved=$((saved + before - after))
+        count=$((count + 1))
+    done < <(find "$dir" -name '*.png' -print0)
+done
+
+if [ "$count" -eq 0 ]; then
+    echo "optimize_goldens: no PNGs found in: ${DIRS[*]}"
+    exit 0
+fi
+
+# Print a human-readable summary. `bc` is standard on macOS / most linuxes.
+mb=$(echo "scale=2; $saved/1048576" | bc)
+printf "optimize_goldens: %d PNGs processed, saved %.2f MB (%s)\n" "$count" "$mb" "$tool"