Fix warnings - imports, deprecations & lint issues across generated templates

[Arjun544]

Audit all Handlebars templates in templates/flutter/ and fix any warnings
produced by Dart Analyze on the generated output. Focus on:

Checklist:

• Remove unused imports in generated .dart.hbs files
• Replace deprecated Flutter/Dart APIs with current equivalents
• Fix all lint warnings flagged by flutter_lints
• Ensure Dart analyze exits clean (zero errors, zero warnings) for
  every architecture + flag combination
• Test with at least: Clean Architecture, MVVM, Feature-First ×
  Riverpod, Bloc, Provider

How to test:

• Run bun run --watch scripts/template-dev.ts
• Check terminal output for Dart analyze warnings
• See docs/template-development.md for full dev loop

References:

• templates/flutter/
• scripts/template-dev.ts
• docs/template-development.md

[Harshit-0413]

Hi, I'd like to work on this. I'll go through the templates and fix the warnings across all architecture combinations.

[Arjun544]

Go ahead. Im here to answer any question 👏🏻

[Harshit-0413]

Hi! I've opened a PR that fixes analyzer issues and deprecated API usage across the templates.

PR: #18

Let me know if any changes are needed 🙂

[Harshit-0413]

Hi @Arjun544, I've pushed the fix for the AppLogger import issue in app_config.dart.hbs. PR #18 is updated. Let me know if anything else needs changing!