feat(release): publish SHA-256 sums and verify them in install.sh/update.sh (#6393)

* feat(release): publish SHA-256 sums and verify them in install.sh/update.sh

The installer and updater fetched the release archive and extracted it
after checking only that the file is not empty, and the release workflow
published no checksums. TLS protects the transport, not the bytes: a
truncated or swapped asset, a bad mirror or a TLS-terminating proxy was
installed as root. #5396 added this verification for the Xray archive;
the panel's own archive was the remaining unverified download.

Publish <asset>.sha256 next to every release archive (Linux and Windows)
and verify it before extracting. A mismatch aborts the install; a missing
sidecar, which every release before this change has, only warns, so
installing older tags keeps working.

Assisted-by: Claude Code:claude-fable-5-1

* fix(install): fail closed when the checksum sidecar cannot be fetched

Review follow-up. Any curl failure on the sidecar (5xx, reset, DNS) was
treated as "no checksum published", so whoever can swap the archive
could also drop the 90-byte sidecar request and skip the check. Only a
404, which every release before the sidecar existed returns, is still
tolerated with a warning; every other outcome aborts and removes the
downloaded archive.

Assisted-by: Claude Code:claude-fable-5-1

* fix(install): restore the closing brace lost in the main merge

.github/workflows/release.yml

@@ -183,13 +183,17 @@ jobs:
           cd ../..
 
       - name: Package
-        run: tar -zcvf x-ui-linux-${{ matrix.platform }}.tar.gz x-ui
+        run: |
+          tar -zcvf x-ui-linux-${{ matrix.platform }}.tar.gz x-ui
+          sha256sum x-ui-linux-${{ matrix.platform }}.tar.gz > x-ui-linux-${{ matrix.platform }}.tar.gz.sha256
 
       - name: Upload files to Artifacts
         uses: actions/upload-artifact@v7
         with:
           name: x-ui-linux-${{ matrix.platform }}
-          path: ./x-ui-linux-${{ matrix.platform }}.tar.gz
+          path: |
+            ./x-ui-linux-${{ matrix.platform }}.tar.gz
+            ./x-ui-linux-${{ matrix.platform }}.tar.gz.sha256
 
       - name: Upload files to GH release
         uses: svenstaro/upload-release-action@v2
@@ -197,8 +201,8 @@ jobs:
         with:
           repo_token: ${{ secrets.GITHUB_TOKEN }}
           tag: ${{ github.ref_name }}
-          file: x-ui-linux-${{ matrix.platform }}.tar.gz
-          asset_name: x-ui-linux-${{ matrix.platform }}.tar.gz
+          file: x-ui-linux-${{ matrix.platform }}.tar.gz*
+          file_glob: true
           overwrite: true
           prerelease: true
 
@@ -316,12 +320,16 @@ jobs:
         shell: pwsh
         run: |
           Compress-Archive -Path .\x-ui -DestinationPath "x-ui-windows-amd64.zip"
+          $hash = (Get-FileHash x-ui-windows-amd64.zip -Algorithm SHA256).Hash.ToLower()
+          [IO.File]::WriteAllText("$PWD\x-ui-windows-amd64.zip.sha256", "$hash  x-ui-windows-amd64.zip`n")
 
       - name: Upload files to Artifacts
         uses: actions/upload-artifact@v7
         with:
           name: x-ui-windows-amd64
-          path: ./x-ui-windows-amd64.zip
+          path: |
+            ./x-ui-windows-amd64.zip
+            ./x-ui-windows-amd64.zip.sha256
 
       - name: Upload files to GH release
         uses: svenstaro/upload-release-action@v2
@@ -329,8 +337,8 @@ jobs:
         with:
           repo_token: ${{ secrets.GITHUB_TOKEN }}
           tag: ${{ github.ref_name }}
-          file: x-ui-windows-amd64.zip
-          asset_name: x-ui-windows-amd64.zip
+          file: x-ui-windows-amd64.zip*
+          file_glob: true
           overwrite: true
           prerelease: true
 
@@ -398,4 +406,4 @@ jobs:
               --target "${COMMIT}" --title "Dev build ${short}" --notes "${notes}"
           fi
 
-          retry gh release upload dev-latest dev-artifacts/*.tar.gz dev-artifacts/*.zip --clobber
+          retry gh release upload dev-latest dev-artifacts/*.tar.gz dev-artifacts/*.zip dev-artifacts/*.sha256 --clobber