fix(docker): handle sigterm & sigint

[gabemeola]

Issue for this PR

• Fixes Opencode always fails to start properly in Docker #12439 - but doesn't fix the opencode web issue of error: Executable not found in $PATH: "xdg-open"

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Currently running docker run -it ghcr.io/anomalyco/opencode serve never always the process to be gracefully closed with SIGTERM and handles forever. This is because it runs as the ENTRYPOINT on PID 1 with no process handler.

Running with docker flag --init does fix it but this is only for the docker runner and isn't cross platform (e.g. kubernetes).

Instead we bake tini into the image which handles signal forwarding and child reaping.

How did you verify your code works?

~/WEBDEV/tmp/opencode/packages/opencode 11s ❯ docker buildx build --platform linux/arm64 -t opencode-test --load .
[+] Building 0.7s (10/10) FINISHED                                   docker-container:mybuilder
 => [internal] load build definition from Dockerfile                                       0.0s
 => => transferring dockerfile: 870B                                                       0.0s
 => [internal] load metadata for docker.io/library/alpine:latest                           0.3s
 => [internal] load .dockerignore                                                          0.0s
 => => transferring context: 2B                                                            0.0s
 => [base 1/2] FROM docker.io/library/alpine:latest@sha256:a2d49ea686c2adfe3c992e47dc3b5e  0.0s
 => => resolve docker.io/library/alpine:latest@sha256:a2d49ea686c2adfe3c992e47dc3b5e7fa6e  0.0s
 => [internal] load build context                                                          0.0s
 => => transferring context: 195B                                                          0.0s
 => CACHED [base 2/2] RUN apk add libgcc libstdc++ ripgrep tini                            0.0s
 => CACHED [build-arm64 1/1] COPY dist/opencode-linux-arm64-musl/bin/opencode /usr/local/  0.0s
 => CACHED [stage-3 1/1] RUN opencode --version                                            0.0s
 => exporting to docker image format                                                       0.2s
 => => exporting layers                                                                    0.0s
 => => exporting manifest sha256:f68e6670a7e68fc1798eb39e5a89c56396a8d2c65247ec39e47c6f75  0.0s
 => => exporting config sha256:cc45a97f594b9108cb6c660778b629c5e35fc10e3a2e3b0da1e4d2a10e  0.0s
 => => sending tarball                                                                     0.2s
 => importing to docker                                                                    0.0s

View build details: docker-desktop://dashboard/build/mybuilder/mybuilder0/pf4iengevap7kf510kmz97l17
~/WEBDEV/tmp/opencode/packages/opencode ❯ docker run -it opencode-test serve
Warning: OPENCODE_SERVER_PASSWORD is not set; server is unsecured.
opencode server listening on http://127.0.0.1:4096
^C⏎                                                                                             ~/WEBDEV/tmp/opencode/packages/opencode ❯

Screenshots / recordings

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Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

If you do not follow this template your PR will be automatically rejected.

[github-actions]

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[github-actions]

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