Use mise to install zig + go in release CI; cut 0.0.4

`mlugg/setup-zig` was chasing mirrors for ~4 minutes on every run
(see v0.0.1 / v0.0.2 logs) and `actions/setup-go` was spending
another ~4 minutes downloading Go before patterm started building.
mise already manages the project's zig pin; adding `go = "1.26.3"`
to `.mise.toml` (matching go.mod) lets `jdx/mise-action@v2` install
both with one cached step. Subsequent runs reuse the mise cache
instead of re-resolving mirror URLs and re-downloading toolchains.

Also adds an `actions/cache@v4` step for `~/.cache/go-build` and
`~/go/pkg/mod` keyed on `go.sum` so `go build` itself doesn't
re-pull modules every tag push.

.gitea/workflows/release.yml

@@ -11,14 +11,19 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - uses: actions/setup-go@v5
+      - uses: jdx/mise-action@v2
         with:
-          go-version-file: go.mod
           cache: true
 
-      - uses: mlugg/setup-zig@v2
+      - name: Cache Go modules
+        uses: actions/cache@v4
         with:
-          version: 0.15.2
+          path: |
+            ~/.cache/go-build
+            ~/go/pkg/mod
+          key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+          restore-keys: |
+            ${{ runner.os }}-go-
 
       - name: Build libghostty-vt
         run: make deps