feat: add script version history (#3085)

* feat: add script version history

* fix: validate canonical save-as paths before backup

* fix: stack script history footer on small screens

scripts/benchmark-script-history.cjs

@@ -0,0 +1,39 @@
+// Reproducible storage comparison, without touching actual script history.
+const fs = require('node:fs');
+const path = require('node:path');
+const zlib = require('node:zlib');
+for (const file of ['sample/notify.js', 'shell/task.sh']) {
+  const source = fs.readFileSync(path.join(__dirname, '..', file), 'utf8');
+  const versions = Array.from({ length: 20 }, (_, i) => ({
+    content: source + '\n// edit ' + i,
+  }));
+  const raw = Buffer.from(JSON.stringify(versions));
+  const strategies = {
+    gzipSeparate: () =>
+      versions.reduce(
+        (sum, version) => sum + zlib.gzipSync(version.content).length,
+        0,
+      ),
+    gzipBundle: () => zlib.gzipSync(raw).length,
+    brotliBundle: () =>
+      zlib.brotliCompressSync(raw, {
+        params: {
+          [zlib.constants.BROTLI_PARAM_QUALITY]: 4,
+          [zlib.constants.BROTLI_PARAM_LGWIN]: 22,
+        },
+      }).length,
+  };
+  for (const [strategy, compress] of Object.entries(strategies)) {
+    const start = performance.now();
+    const bytes = compress();
+    console.log(
+      JSON.stringify({
+        file,
+        strategy,
+        rawBytes: raw.length,
+        bytes,
+        ms: +(performance.now() - start).toFixed(2),
+      }),
+    );
+  }
+}