feat(release): make the signing-free install work with nothing but Windows

The manual install path still needed 7-Zip, which the target machine does not
have, so "installable without a certificate" was not yet true.

The channel now also publishes the app as byte-split zip parts, and the install
script joins them and extracts with the built-in Windows Expand-Archive after
verifying every part and the joined archive. Version 1.3.1 republishes the
channel from a single build, because a version's artifacts can only match one
build and published volumes are never overwritten.

docs/map/10-feature-catalog.md

@@ -193,7 +193,7 @@ Status quick-reference: `[x]` done+verified · `[~]` partial/unverified · `[ ]`
 | INFRA-13 | Site deploy (Cloudflare Pages + GitHub Pages) | [x] | `.forgejo/workflows/deploy-site.yml`, `.github/workflows/deploy-site.yml` |
 | INFRA-15 | Update & release system | [x] | Canonical Forgejo feed + channels/policy (`release/update-policy.json`, `src/main/update-policy.ts`), canonical publisher `scripts/ci/publish-forgejo-release.mjs`, legacy GitLab mirror; `npm run release:metadata:test`. v1.1.0 was published to Forgejo on 2026-09-15; product version moved to `1.2.0` as a forward-fix with CI-only publication, a same-version re-release guard, and download centers that link the feed instead of repository paths. `1.3.0` (2026-09-18) carries the local-STT fixes; Windows publication still needs the CI signing secrets (`11` GAP-REL-02). |
 | INFRA-16 | Desktop STT engine packaging | [x] | `apps/desktop/scripts/setup-sidecar.mjs` + `build-sidecar.mjs`, `electron-builder.yml` `extraResources` (`sidecar-dist/sidecar` → `resources/sidecar`, `resources/ffmpeg`), and `scripts/ci/verify-sidecar-bundle.mjs` run in `package-windows`/`package-macos` before electron-builder. Verified on the real bundle: `sidecar.exe` + `_internal` including `faster_whisper/assets/silero_vad_v6.onnx`, plus a packaged-engine transcription round-trip on GPU. |
-| INFRA-17 | 서명 없는 배포 채널 (portable + Scoop) | [x] | `scripts/ci/build-portable.mjs` (95MiB 7z 분할 볼륨 + Scoop 매니페스트), `scripts/ci/publish-portable-release.mjs`, `scripts/local/install-d3ro-voice.ps1`, `bucket/` 버킷, `.forgejo/workflows/portable.yml`; updater feed와 분리. 2026-09-18 게시 + 실제 설치 검증. |
+| INFRA-17 | 서명 없는 배포 채널 (portable + Scoop) | [x] | `scripts/ci/build-portable.mjs` (95MiB 7z 분할 볼륨 + Scoop 매니페스트), `scripts/ci/publish-portable-release.mjs`, `scripts/local/install-d3ro-voice.ps1`, `bucket/` 버킷, `.forgejo/workflows/portable.yml`; 7z 분할 볼륨(Scoop, 162MiB) + zip 분할 부품(수동 설치, 243MiB, 7-Zip 불필요); updater feed와 분리. 2026-09-18 `portable-1.3.1` 게시 + 실제 설치 검증. |
 
 ---