v1.0.0 — multi-flavor rebuild

[ElecTreeFrying]

v1.0.0 — first major release

Rebuilds every snippet from current @nativescript/core (v9.0.20) — a three-major-version leap from the v6.4.0 the original pack targeted — and generates them for five flavors (Angular html, Core xml, Vue, React tsx/jsx, Svelte) from one neutral model, so the snippet JSON and the docs can no longer drift. 805 snippets total.

No tracking issue, by design: the rationale, scope, and full change list already live in the repo and this PR carries the diff — an issue would just duplicate them with no audience.

• What changed → CHANGELOG.md → v1.0.0 (Added / Changes / Removed)
• Design & generation pipeline → SPEC.md
• Manual QA → qa/checklists/ (run general.md first, then per-flavor)

22 commits, grouped by concern: generator-rendered per-flavor snippets, docs (README / SPEC / SUPPORT / reference), the qa/ harness, and tooling/ignore rules. No version bump — vsce publish owns that.

⚠️ Do not publish until 2026-06-28. Merging to main ahead of that is fine and is actually preferred: the demo .gifs are excluded from the .vsix, and vsce rewrites their relative paths to raw main URLs at publish time — so they must already be on the default branch before the Marketplace listing goes out.