ci: feedback-theme.css token lint — validate required --feedback-* tokens are defined in each app

[wcmchenry3-stack]

Summary

The feedback widget theme contract (.claude/policies/feedback-widget-tokens.md) defines a set of required --feedback-* CSS custom properties. Currently there is no automated check that an app's frontend/feedback-theme.css actually defines all of them — enforcement is manual.

This issue tracks adding a reusable called workflow (called-feedback-token-lint.yml) that:

1. Reads the machine-readable schema at schemas/feedback-widget-tokens.schema.json (already exists)
2. Extracts all tokens marked "required": true
3. Checks the app's frontend/feedback-theme.css to confirm every required token is defined (i.e. a --feedback-<token>: declaration is present)
4. Fails the check if any required token is missing, listing exactly which ones

Acceptance criteria

• called-feedback-token-lint.yml added to .github/workflows/
• Uses schemas/feedback-widget-tokens.schema.json as the source of truth — no hardcoded token list in the workflow
• Accepts a feedback-theme-path input (default: frontend/feedback-theme.css) so apps with non-standard layouts can override
• Reports missing tokens clearly in the step output
• Wired into ci-cloudflare-workers.yml or a new caller so it runs on PRs that touch frontend/feedback-theme.css
• Advisory by default — follows the same policy-enforcement.yml pattern as the design-token check

Related

• Token contract: .claude/policies/feedback-widget-tokens.md
• Schema: schemas/feedback-widget-tokens.schema.json
• Noted as follow-up in policy doc: "A dedicated lint step validating that all required --feedback-* tokens are defined in each app's feedback-theme.css will be added in a follow-up story"
• App issues: feat(gaming_app): feedback form UI widget — themed bug/feature submission with screenshot and session log attachment #110 (gaming_app widget), feat(book_app): feedback form UI widget — themed bug/feature submission with screenshot and session log attachment #111 (book_app widget)