Fix dashboard service link creation

[ZacharyZcR]

Summary

• accept bare service addresses such as 192.168.1.10:8080 by normalizing them to http://...
• apply the same service-link URL normalization on the backend routes
• surface add failures in the Service Links card instead of silently resetting the button state
• add unit coverage for service-link URL normalization

Fixes Termix-SSH/Support#893.

Tests

• git diff --check
• npx prettier --check src/ui/lib/service-link-url.ts src/backend/database/routes/service-link-url.ts src/backend/database/routes/service-link-url.test.ts src/ui/api/dashboard-api.ts src/ui/dashboard/DashboardTab.tsx src/backend/database/routes/dashboard-service-links-routes.ts src/ui/locales/en.json
• npx eslint src/ui/lib/service-link-url.ts src/backend/database/routes/service-link-url.ts src/backend/database/routes/service-link-url.test.ts src/ui/api/dashboard-api.ts src/ui/dashboard/DashboardTab.tsx src/backend/database/routes/dashboard-service-links-routes.ts
• npx vitest run src/backend/database/routes/service-link-url.test.ts
• npm run type-check
• npm run build:backend (fails on existing unrelated missing serialport types: src/backend/serial/serial.ts imports serialport)