infra[notask]: consolidate 13 on-pr-close-<pkg>.yml into on-pr-close.yml

[sidj-thr]

Summary

• Consolidates the 13 normal on-pr-close-<pkg>.yml files (ephemeral PR-version GPR cleanup on pull_request: closed) into one on-pr-close.yml.
• No nx, no matrix by design: the reusable public-delete-npm-versions.yml already loops a space-separated packages list and auto-scopes to pr-<n> from the event, and is a safe no-op for packages with no such version. Deletion is idempotent per package, so forcing nx-affected onto a closed-PR event would add cost with no functional benefit.
• Preserves legacy behavior exactly: dry-run: true forced on pull_request events (real deletes only via manual dispatch with dry-run: false), paths: packages/** scoping.
• 3 retired dispatch-only stubs (translation-nmtcpp, transcription-parakeet, transcription-whispercpp) are left as carve-outs — not part of the auto-close trigger.
• Additive only — legacy on-pr-close-<pkg>.yml files not deleted this pass.

Test plan

• actionlint clean (also validates the reusable-call input names against public-delete-npm-versions.yml)
• act -n resolves and runs the reusable job graph on a pull_request event
• Live PR-close test to confirm the multi-package packages list behaves as expected end-to-end

🤖 Generated with Claude Code

[github-actions]

License compliance — clean

No new dependency license findings in this PR.

Warn-only (shadow) mode — this check does not block merges yet.

Updated automatically by the canonical license compliance workflow.

NOTICE presence (advisory)

Missing NOTICE (advisory, does not block):

• ./.github/actions/release-merge-guard
• ./packages/vla-ggml/sim/server
• ./packages/asr-ggml/benchmarks/server
• ./packages/embed-llamacpp/benchmarks/performance
• ./packages/embed-llamacpp/benchmarks/server
• ./packages/llm-llamacpp/benchmarks/performance
• ./packages/llm-llamacpp/benchmarks/server
• ./packages/ggml-coload-smoke
• ./packages/sdk/e2e
• ./packages/fabric/test/integration
• ./docs/website

[github-actions]

Workflow security (shadow mode)

zizmor found 1084 finding(s) in .github/ (highest severity: high). This check is warn-only and does not block the merge.

Findings are annotated inline on the changed files and listed in the job summary.

Reproduce locally:

pipx run zizmor==1.27.0 --offline .github/