Routing hardening: validate path/query params (avoid `!` crashes)

[syed-reza98]

Why

Routes frequently use state.pathParameters['id']! which can crash on malformed deep links.

Current code

• lib/utils/routes.dart: many ! extractions

Tasks

• Create small helper(s) to safely read required params and return an error screen when missing
• Apply to all routes with path/query parameters
• Add minimal test cases or manual reproduction steps for bad URLs

Acceptance criteria

• Invalid/missing params do not crash; user sees a friendly error page and a way home
• Valid deep links keep working

References

• Stability and deep-link support in docs + current router usage

[syed-reza98]

Closed as completed via PR #71.