refactor: rename trigger-website-update to dispatch-with-fallback

[baxyz]

Summary

• Per discussion: trigger-website-update was too helpers4-specific for a repo whose stated purpose is publishing generic actions to the GitHub Marketplace. Its actual mechanics were already 100% generic (mint a GitHub App token → repository-dispatch, retry with a fallback identity on failure) — only the name and the target-owner: helpers4/target-repo: website defaults were org-specific.
• Renamed trigger-website-update → dispatch-with-fallback, made target-owner/target-repo required (no defaults) instead of defaulting to helpers4/website
• Verified the other 3 actions (conventional-commits, setup-pnpm, pr-status-comment) have no comparable org-specific defaults — scopes.json/.vscode/settings.json are generic filename conventions, not helpers4-branded
• Updated this repo's own usage (release.yml) to pass target-owner: helpers4 / target-repo: website explicitly
• Follow-up PRs needed in devcontainer, typescript, .github to update their call sites to the new name + explicit target inputs — opening those next, this is deliberately first so the new path exists on main before they reference it

Test plan

• CI: shellcheck, manifest validation, existing smoke tests for the other 2 actions unaffected
• Confirm dispatch-with-fallback isn't referenced anywhere by its old name after merge

🤖 Generated with Claude Code

[github-actions]

✅ PR Validation Passed

All checks passed!

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📋 Pipeline Status

	Job	Status
✅	🧾 Conventional Commits	passing
✅	🐚 ShellCheck	passing
✅	🧪 Action Tests	passing
✅	📄 Manifest Validation	passing
✅	📦 setup-pnpm Tests	passing
✅	💬 pr-status-comment Tests	passing

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_{🤖 Generated by @helpers4 CI • 2026-07-29}