fix(ci): harden publish workflows with provenance and Sigstore verification

[henrypalacios]

Summary

Port the hardened publish workflow pattern from quickswap-default-token-list/.github/workflows/publish.yaml to both SDK publish workflows. Reviewed via judgment-day dual blind review — APPROVED on round 1.

Structural changes

• Separate bump-and-tag job before publish-npm with atomic git push --atomic of branch + tag and a 3-attempt retry on non-fast-forward.
• Tag pre-check via git ls-remote fails fast on collision.
• publish-npm checks out the exact SHA produced by bump-and-tag (workflow_dispatch path) or the tag ref (push:tags recovery path).
• Concurrency groups (publish-sdk, publish-protocol-core) serialize per-package dispatches.

Operational improvements

• Tag commit validation on the release path (ancestry + subject + author).
• Sigstore signature verification post-publish via npm audit signatures --include-attestations with 10-attempt retry.
• SLSA predicate type assertion in registry metadata.
• --ignore-scripts on all pnpm and npm install invocations.
• Idempotent GitHub Release creation (gh release view guard, heredoc-based notes).
• Robust check_version with explicit E404 detection and retry.
• npm pinned to 11.13.0 in verify-publish (--include-attestations requires >= 11.12.0).
• Polling-based registry propagation (replaces fixed sleep 30).
• Real dry-run path with npm publish --dry-run preview.

Test plan

• Manual workflow_dispatch with dry_run: true for publish-sdk.yaml
• Manual workflow_dispatch with dry_run: true for publish-protocol-core.yaml
• Real publish of @quickswap-defi/protocol-core patch bump via workflow_dispatch after merge
• Confirm Sigstore verification passes (registry propagation up to ~2.5 min)
• Confirm GitHub Release is created with correct title and notes
• Confirm tag is on main and signed commit author matches the release bot

Reference

• Source: quickswap-default-token-list/.github/workflows/publish.yaml
• Linted with actionlint — no errors