update docs

Author: kjk

.gitignore

@@ -56,3 +56,4 @@ pipe-preview-results
 nul
 docs/scratch.txt
 build.log
+bin/zopflipng.exe

cmd/bun.lock

@@ -0,0 +1,62 @@
+import { existsSync, readdirSync, statSync } from "node:fs";
+import { join } from "node:path";
+
+const binDir = join("bin");
+const zopflipngPath = join(binDir, "zopflipng.exe");
+const imgDir = join("docs", "md", "img");
+const downloadUrl = "https://drpleaserespect.github.io/drpleaserespect-webassets/compiled_binaries/google/zopflipng.exe";
+
+async function ensureZopflipng(): Promise<void> {
+  if (existsSync(zopflipngPath)) {
+    console.log(`using cached ${zopflipngPath}`);
+    return;
+  }
+  console.log(`downloading zopflipng.exe from ${downloadUrl}`);
+  const resp = await fetch(downloadUrl);
+  if (!resp.ok) {
+    throw new Error(`download failed: ${resp.status} ${resp.statusText}`);
+  }
+  const data = await resp.arrayBuffer();
+  await Bun.write(zopflipngPath, data);
+  console.log(`saved ${zopflipngPath}`);
+}
+
+async function compressImage(pngPath: string): Promise<void> {
+  const sizeBefore = statSync(pngPath).size;
+  // zopflipng overwrites in-place when input and output are the same
+  const proc = Bun.spawn([zopflipngPath, "-y", pngPath, pngPath], {
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+  const exitCode = await proc.exited;
+  if (exitCode !== 0) {
+    const stderr = await new Response(proc.stderr).text();
+    console.log(`  warning: zopflipng failed on ${pngPath}: ${stderr.trim()}`);
+    return;
+  }
+  const sizeAfter = statSync(pngPath).size;
+  const saved = sizeBefore - sizeAfter;
+  if (saved > 0) {
+    console.log(`  ${pngPath}: ${sizeBefore} -> ${sizeAfter} (saved ${saved} bytes)`);
+  } else {
+    console.log(`  ${pngPath}: ${sizeBefore} bytes (already optimal)`);
+  }
+}
+
+async function main(): Promise<void> {
+  await ensureZopflipng();
+
+  const files = readdirSync(imgDir)
+    .filter((f) => f.toLowerCase().endsWith(".png"))
+    .map((f) => join(imgDir, f));
+
+  console.log(`compressing ${files.length} PNG files in ${imgDir}`);
+  for (const file of files) {
+    await compressImage(file);
+  }
+  console.log("done");
+}
+
+if (import.meta.main) {
+  await main();
+}