Use stable mirrors for release downloads

[heqi]

Summary

• Download skaffold binaries from the official storage.googleapis.com/skaffold/releases bucket instead of GitHub Release assets.
• Download jq binaries from the SourceForge jq mirror instead of GitHub Release assets.
• Download hub and yq binaries from SourceForge mirrors instead of GitHub Release assets.
• Download kustomize through the official GitHub release asset API, which avoids the flaky github.com/.../releases/download asset page while staying on GitHub-owned infrastructure.
• Add an action-level retry around @actions/tool-cache.downloadTool so transient 504s on remaining release assets, such as hub, get another full download attempt.
• Update yq integration coverage to 4.53.2, which is available from the yq SourceForge mirror.
• Add regression tests for the Linux x64 skaffold 2.3.1, jq 1.6, hub 2.14.2, yq 4.53.2, and kustomize 3.5.4 download paths, plus the shared download retry and zip extraction behavior.
• Rebuild dist/index.js so the shipped action uses the new URLs and retry wrapper.

Validation

• corepack yarn test __test__/installers/skaffold-url.test.ts
• corepack yarn test __test__/installers/jq-url.test.ts
• corepack yarn test __test__/installers/utils-retry.test.ts
• corepack yarn test __test__/installers/hub-url.test.ts __test__/installers/yq-url.test.ts __test__/installers/utils-retry.test.ts
• corepack yarn test __test__/installers/hub-url.test.ts __test__/installers/yq-url.test.ts __test__/installers/utils-retry.test.ts __test__/installers/jq-url.test.ts __test__/installers/skaffold-url.test.ts
• corepack yarn test __test__/installers/kustomize-url.test.ts __test__/installers/utils-retry.test.ts
• corepack yarn test __test__/installers/kustomize-url.test.ts __test__/installers/hub-url.test.ts __test__/installers/yq-url.test.ts __test__/installers/utils-retry.test.ts __test__/installers/jq-url.test.ts __test__/installers/skaffold-url.test.ts
• corepack yarn test __test__/installers/utils-retry.test.ts __test__/installers/jq-url.test.ts __test__/installers/skaffold-url.test.ts
• corepack yarn format-check
• corepack yarn build
• Fresh mono CD - web workflow dispatch on feat/cd: https://github.com/coscene-io/mono/actions/runs/27123224005

The fresh mono run passed through Set up CD tools and completed successfully.