Remove frontend billing pages and trial UI components

[BrewingCoder]

Parent: #25 — Remove all SaaS billing code

Do this LAST — after all backend billing fields are removed

What to Remove

Billing Pages

• src/frontend/src/pages/Billing/ — entire directory (utils, components, pages)
• src/frontend/src/pages/Billing/utils/utils.ts — getTrialEndDateMessage() and related

Trial UI

• src/frontend/src/components/Header/Header.tsx:831 — trial end date banner

Generated GraphQL Types

• After backend schema changes, run yarn codegen to regenerate
• Remove any frontend code referencing deleted billing GraphQL fields

Route Configuration

• Remove billing page routes from router config

Strategy

This should be done AFTER the backend billing fields are removed and GraphQL schemas regenerated. The frontend changes will largely be guided by TypeScript errors after codegen.

Test Plan

• Wait for backend billing removal PRs to merge
• Run yarn codegen to regenerate types
• Fix all TypeScript errors (remove references to deleted fields)
• Remove billing pages and components
• Remove billing routes
• yarn types:check passes
• yarn build passes
• yarn test passes
• Manual smoke test: dashboard loads without billing pages

🤖 Generated with Claude Code

[github-actions]

AI Triage: Remove frontend billing pages, trial UI components, and related GraphQL types as part of SaaS billing code removal.

Labels applied: tech-debt, billing-removal, area:frontend, priority:medium, component:graphql