Update runtime to gnome sdk 50 and command, modify build process

[fastrizwaan]

Updated runtime version and command, modified build commands for better file extraction, and changed source URLs to the latest version.

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[fastrizwaan]

this builds and runs fine on local machine. but ai.opencode.opencode.metainfo.xml is missing. even the github is missing that file:

$ find . -iname "*meta*"
./packages/ui/src/assets/icons/file-types/folder-meta.svg
./packages/ui/src/assets/icons/file-types/folder-meta-open.svg
./packages/opencode/test/plugin/meta.test.ts
./packages/opencode/test/fixture/plugin-meta-worker.ts
./packages/opencode/src/server/routes/instance/httpapi/groups/metadata.ts
./packages/opencode/src/plugin/meta.ts
./packages/desktop/scripts/copy-metainfo.ts
./packages/core/src/github-copilot/chat/openai-compatible-metadata-extractor.ts
./packages/core/src/github-copilot/chat/get-response-metadata.ts

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🚧 Started test build.

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