Using alba-inertia for serialization

[skryukov]

This PR introduces a layer of serialization and frontend type safety by integrating the Alba and Typelizer gems. It replaces manual serialization and hand-written TypeScript types with auto-generated serializers and types, streamlining the way data is shared between Rails controllers and Inertia.js React components. The changes improve maintainability, consistency, and developer experience across the stack.

• Controllers now use Alba-based resource serializers (e.g., SharedPropsResource, TopicsIndexResource) instead of manual .as_json calls and explicit prop hashes, simplifying data preparation for Inertia responses.
• Manual TypeScript interfaces in app/frontend/types.ts are removed and replaced with auto-generated types in app/frontend/types/serializers/, ensuring the frontend matches backend data structures exactly.
• All React components and pages are updated to use the new auto-generated types.
• All keys are transformed to lowerCamelCase via transform_keys :lower_camel

Added gems:

• Alba — JSON serializer for Ruby
• Typelizer — A TypeScript type generator for Ruby serializers
• Alba::Inertia - Support for all Inertia prop types, lazy evaluation for all props by default (no lambdas required), auto-detection of serialization classes based on controller/action naming
• Listen - Watches for serialization classes changes to update typescript types on-the-fly