fix(ci): harden GitHub Actions workflows (#250)

[hf-security-analysis]

Automated hardening of the workflow files flagged on #250.

Warning

This changes when the workflow runs and what it can reach. Both triggers and permissions were rewritten in .github/workflows/ci.yml. Read the diff before merging — either one can change what the workflow is able to do.

Targets main. Files changed:

• .github/workflows/ci.yml

Fixed by this PR:

• HIGH excessive-permissions (zizmor) — .github/workflows/ci.yml:11

Permissions

.github/workflows/ci.yml

job	granted	why
test-macos	contents: read	Only checks out the repo (actions/checkout), restores an actions/cache entry, and runs swift format/build/test locally, so contents: read for checkout is all that is needed; caching within the same repo requires no token scope.
build-watchos	contents: read	Checks out the repo and runs xcodebuild locally; no API calls, so contents: read for actions/checkout suffices.
test-linux	contents: read	Checkout plus actions/cache and swift build/test inside a container; no step writes to the repository or PR, so only contents: read is required (the workflow-level pull-requests: write is unused).

Anything not listed above keeps the permissions it had. To measure a job this could not read, add GitHubSecurityLab/actions-permissions/monitor to it and run the workflow — it reports the minimum the run actually used.

Pinning changes come from pinact and are mechanical. Any other change was generated by Claude — read it before merging.

Closes huggingface/tracking-issues#949