ci(release): build linux-x86_64 natively on the new amd64 runner

A native x86_64 Gitea Actions runner (hostinger-runner, label
linux-amd64) is now available alongside the two aarch64 runners
(oracle-runner/-b, label linux-arm64). Routes the linux-x86_64 leg of
the cli and gui release matrices to it instead of cross-compiling it
from an aarch64 host, same change as the Guará repository.

- matrix.include gets an explicit runner field per platform
  (linux-arm64 for aarch64, linux-amd64 for x86_64 and windows);
  runs-on: ${{ matrix.runner }} picks it per job. windows is pinned to
  linux-amd64 explicitly rather than relying on the ubuntu-latest
  alias, since that alias has already been reassigned once between
  the aarch64 and the x86_64 runner on this Gitea instance.
- The "Platform cross-linker" step (gcc-x86-64-linux-gnu) only runs
  when NOT on the native amd64 runner, since a native build needs no
  cross-linker.
- scripts/build-gui.sh and scripts/package-cli.sh are intentionally
  left untouched: both already branch on `uname -m` and take the
  simple native path when run on x86_64, so no script change was
  needed. The existing cross-compile path (qemu wrappers, the ELF
  launcher that survives tauri-bundler's dd patch) stays in place as a
  dormant fallback in case the single amd64 runner is ever
  unavailable — deliberately kept, not deleted.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VAyr8d7HuAdUGB6aA5xmDD

.gitea/workflows/release.yml

@@ -48,22 +48,22 @@ jobs:
   cli:
     name: CLI (${{ matrix.platform }})
     needs: release
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.runner }}
     env:
       CARGO_TARGET_DIR: /opt/hostedtoolcache/cargo-target/sabia-release-cli-${{ matrix.platform }}
     strategy:
       fail-fast: false
       matrix:
         include:
-          - { platform: linux-aarch64, target: aarch64-unknown-linux-gnu, apt: "" }
+          - { platform: linux-aarch64, target: aarch64-unknown-linux-gnu, apt: "", runner: linux-arm64 }
-          - { platform: linux-x86_64, target: x86_64-unknown-linux-gnu, apt: "gcc-x86-64-linux-gnu" }
+          - { platform: linux-x86_64, target: x86_64-unknown-linux-gnu, apt: "gcc-x86-64-linux-gnu", runner: linux-amd64 }
     steps:
       - uses: actions/checkout@v7
       - uses: dtolnay/rust-toolchain@stable
         with:
           targets: ${{ matrix.target }}
       - name: Platform cross-linker
-        if: ${{ matrix.apt != '' }}
+        if: ${{ matrix.apt != '' && matrix.runner != 'linux-amd64' }}
         run: scripts/apt-install.sh /opt/hostedtoolcache/apt-cache/cli-x86_64 ${{ matrix.apt }}
       - name: Build and package
         run: scripts/package-cli.sh "${{ gitea.ref_name }}" "${{ matrix.platform }}" "${{ matrix.target }}" | tee packages.txt
@@ -76,7 +76,7 @@ jobs:
   gui:
     name: Desktop app (${{ matrix.platform }})
     needs: release
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.runner }}
     env:
       CARGO_TARGET_DIR: /opt/hostedtoolcache/cargo-target/sabia-release-gui-${{ matrix.platform }}
       TAURI_SIGNING_PRIVATE_KEY: ${{ secrets.SABIA_TAURI_SIGNING_PRIVATE_KEY || secrets.TAURI_SIGNING_PRIVATE_KEY }}
@@ -84,7 +84,10 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        platform: [linux-aarch64, linux-x86_64, windows]
+        include:
+          - { platform: linux-aarch64, runner: linux-arm64 }
+          - { platform: linux-x86_64, runner: linux-amd64 }
+          - { platform: windows, runner: linux-amd64 }
     steps:
       - uses: actions/checkout@v7
       - uses: dtolnay/rust-toolchain@stable