Release: CLI 4.0.3 and skill 4.2.1 with signed Windows engine (#743)

* Release: prepare signed engine 0.1.2

Bump engine and platform-package pins for the first Azure-signed Windows release. Keep this branch off main until release assets and all platform packages are published; refresh bun.lock after publication.

AI assistance: Codex.

* Release: CLI 4.0.3 and skill 4.2.1

Ship the verified signed Windows engine 0.1.2. Refresh provider/plugin version metadata and engine pins intentionally for release. All five platform packages are published and byte-verified. AI assistance: Codex.

.github/skills/impeccable/SKILL.md

@@ -1,7 +1,7 @@
 ---
 name: impeccable
 description: Use when the user wants to design, redesign, shape, critique, audit, polish, clarify, distill, harden, optimize, adapt, animate, colorize, extract, or otherwise improve a frontend interface. Covers websites, landing pages, dashboards, product UI, app shells, components, forms, settings, onboarding, and empty states. Handles UX review, visual hierarchy, information architecture, cognitive load, accessibility, performance, responsive behavior, theming, anti-patterns, typography, fonts, spacing, layout, alignment, color, motion, micro-interactions, UX copy, error states, edge cases, i18n, and reusable design systems or tokens. Also use for bland designs that need to become bolder or more delightful, loud designs that should become quieter, live browser iteration on UI elements, or ambitious visual effects that should feel technically extraordinary. Not for backend-only or non-UI tasks.
-version: 4.2.0
+version: 4.2.1
 user-invocable: true
 argument-hint: "[shape · audit|critique · animate|bolder|colorize|delight|layout|overdrive|quieter|typeset · adapt|clarify|distill · harden|onboard|optimize|polish · init|document|extract|live] [target]"
 license: Apache 2.0

.github/skills/impeccable/scripts/VERSION

@@ -1 +1 @@
-0.1.1
+0.1.2