chore(ci): add explicit GITHUB_TOKEN permissions to workflows

[ilhan007]

Summary

Adds explicit top-level permissions blocks to all GitHub Actions workflow files. This follows the principle of least privilege and prepares the repository for the upcoming enforcement of read-only GITHUB_TOKEN permissions by default.

Permissions Applied

Workflow	Permission	Reason
ci.yml	contents: read	Only checks out code and runs build/test — no write access needed
lint.yml	contents: read	Only checks out code and runs linting — no write access needed
deploy.yml	contents: write	Uses JamesIves/github-pages-deploy-action which pushes the built artifacts to the gh-pages branch

Context

GitHub is enforcing read-only default permissions for GITHUB_TOKEN across organizations. Without explicit permissions blocks, workflows that rely on write access (like the deploy workflow) will break once the default changes. Adding explicit declarations now ensures workflows continue to function correctly and documents the intended access level for each.