Parse auth cookies without requiring spaces

[aiirvizionz]

Summary

• accept valid Cookie headers that omit the optional space after semicolons across protected auth/chat/conversation routes
• add regression coverage for backup PIN and salt auth cookie parsing
• leave key-backup to the separate open PR Parse key backup auth cookies without requiring spaces #140 to avoid overlapping changes

Validation

• pnpm exec vitest run --config vitest.api-temp.config.js src/app/api/auth/backup-pin/route.test.js src/app/api/auth/salt/route.test.js (temporary no-plugin config used because the repo Vitest config fails to load @vitejs/plugin-react/Vite in this checkout)
• node --check src/app/api/auth/backup-pin/route.js
• node --check src/app/api/auth/backup-pin/route.test.js
• node --check src/app/api/auth/salt/route.js
• node --check src/app/api/auth/salt/route.test.js
• git diff --check

Note: npx prettier --check ... could not run because the repo Prettier config imports missing prettier-plugin-svelte.