chore: bump version and changelog (v1.4.0.0)

New /make-pdf skill + $P binary.

Turn any markdown file into a publication-quality PDF. Default output is
a 1in-margin Helvetica letter with page numbers in the footer. `--cover`
adds a left-aligned cover page, `--toc` generates a clickable table of
contents, `--watermark DRAFT` overlays a diagonal watermark. Copy-paste
extraction from the PDF produces clean words, not "S a i l i n g"
spaced out letter by letter. CI gate (macOS + Ubuntu) runs a combined-
features fixture through pdftotext on every PR.

make-pdf shells out to browse rather than duplicating Playwright.
$B pdf grew into a real PDF engine with full flag contract (--format,
--margins, --header-template, --footer-template, --page-numbers,
--tagged, --outline, --toc, --tab-id, --from-file). $B load-html and
$B js gained --tab-id. $B newtab --json returns structured output.

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "gstack",
-  "version": "1.3.0.0",
+  "version": "1.4.0.0",
   "description": "Garry's Stack — Claude Code skills + fast headless browser. One repo, one install, entire AI engineering workflow.",
   "license": "MIT",
   "type": "module",