Add release pipeline and upgrade toolchain to TypeScript 7

Publishing infrastructure
- Three Gitea workflows: ci.yml (PRs, non-main pushes), publish-snapshot.yml
  (main -> Gitea under dist-tag @main) and release.yml (tags -> Gitea + npmjs)
- Tag-driven releases as <package-dir>-v<version>; the manifest stays the
  source of truth and release.yml refuses to run if tag and manifest disagree
- Every publish is idempotent: each step checks the registry first, so a run
  that fails on the second registry can simply be re-run
- Hard coverage gate (85% branches) shared by CI, the pre-push hook and local
  runs, since the thresholds live in vitest.config.ts rather than a CI flag
- README.PUBLISH.md documents the whole mechanism

Toolchain
- TypeScript 7 native compiler; drop tsgo and ts-node, use tsx for dev runs
- Biome 1.9 -> 2.x, Vitest 1 -> 4, zod 3 -> 4, inquirer 8 -> 14, pnpm 11.17.0
- Replace inquirer-checkbox-plus-prompt, which is peer-capped at inquirer <9,
  with enquirer's AutoComplete; the CubeSelection contract is unchanged
- Stand in for zod 4's removed z.AnyZodObject with a local AnyObjectSchema

Repo hygiene
- Stop tracking dist/; ignore coverage/, *.tsbuildinfo, .npmrc* and release.json
- Drop package-lock.json in favour of pnpm-lock.yaml

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.nvmrc

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