fix: validate cached token scope

[LeonRuggiero]

Summary

• validate cached Vertesia tokens against every explicitly requested account and project scope
• allow account-only and global requests to reuse valid tokens without requiring absent claims to match
• add regression coverage for project mismatches, account-scoped reuse, and global reuse

Test Plan

• pnpm --filter @vertesia/ui exec vitest run src/session/auth/composable.scope.test.ts (3 tests passed)
• pnpm --filter @vertesia/ui typecheck:test
• pnpm --filter @vertesia/ui lint
• pnpm --filter @vertesia/ui build
• local UI restarted under Overmind and returned HTTP 200
• aggregate pnpm build stopped on a pre-existing @llumiverse/drivers TypeScript error in drivers/src/openai/index.ts:699: InputTokensDetails.cache_write_tokens does not exist