ci: skip the release pipeline when R2 release infrastructure is absent

[thomaswillner]

Problem

The Release Prime Agent workflow (build-binaries.yml) runs on every push to main and has failed on all 4 runs in this repo — the latest two being the doc-only merges of #6 and #9. The build and npm run check steps pass; the failure is always the same:

Run test -n "$PRIME_AGENT_DOWNLOAD_BASE_URL"
  PRIME_AGENT_DOWNLOAD_BASE_URL:            <- empty
Process completed with exit code 1.

PRIME_AGENT_DOWNLOAD_BASE_URL comes from vars.R2_PUBLIC_BASE_URL, which is upstream release infrastructure (together with the R2_* secrets used by the publish job). Neither exists on this fork, so the pipeline can never succeed here — every push to main produces a failed run and the README's Build Binaries badge stays permanently red.

Change

One job-level if on release-context (the root job — build and publish depend on it via needs, so they inherit the skip):

• Push- and tag-triggered runs skip cleanly when R2_PUBLIC_BASE_URL is not configured, instead of failing. The run concludes green with all jobs skipped.
• Repos with the variable configured are byte-for-byte unaffected — the condition is true and everything runs as before, so the change is upstreamable.
• workflow_dispatch is exempt from the gate: an explicit manual release request without infrastructure still runs and fails loudly on the existing test -n guards, rather than silently skipping.

Validation

• YAML parses (yaml.safe_load).
• The condition uses only documented job-level if contexts (vars, github.event_name); undefined repository variables evaluate to '' in expressions, so absence ⇒ skip.
• npm run check clean on the branch (biome 901 files, tsgo, installer render, browser smoke — also re-run by the pre-commit hook at commit time).
• No behavior of the packaging/publish steps themselves is touched; the diff is 5 added lines (comment + condition).

---

Generated by Claude Code