feat: use-context-evaluation-with-newest-engine-version

[Zaimwa9]

Thanks for submitting a PR! Please check the boxes below:

• I have added information to docs/ if required so people know about the feature!
• I have filled in the "Changes" section below?
• I have filled in the "How did you test this code" section below?
• I have used a Conventional Commit title for this Pull Request

Closes #168

This PR upgrades the flagsmith-flag-engine from v6.1.0 to v10.0.3 following the approach from flagsmith-python-client#150, and implements the hide_disabled_flags project setting.

Changes

Engine Migration (v6 → v10)

• Upgraded flagsmith-flag-engine from 6.1.0 to 10.0.3
• Added flagsmith>=5 dependency for TypedDict models and mappers
• Migrated from Pydantic models to TypedDict-based evaluation contexts
• Replaced deprecated engine functions with new get_evaluation_result()
• Used map_environment_document_to_context() and map_context_and_identity_data_to_context() from flagsmith-python-client
• Updated traits handling from list[TraitModel] to dict[str, ContextValue] with backward compatibility validator
• Updated response mappers to work with new flag result format

hide_disabled_flags

• Added _filter_disabled_flags() helper function
• Implemented filtering in src/edge_proxy/environments.py for both /api/v1/flags/ and /api/v1/identities/ endpoints
  ⚠️ Question: What behavior when fetching a single disabled flag with hide_disabled_flags ? 404 or still returning it ?
  EDIT: Had my response here and will implement.

Tests

• Added new tests in tests/test_server.py for hide_disabled_flags functionality
• Added test fixture environment_with_hide_disabled_flags in tests/fixtures/response_data.py

How did you test this code?

Local Integration Testing:
1. Start edge proxy: rye run edge-proxy-serve
2. Test with Node.js SDK pointing to http://localhost:8000/api/v1/
3. Verify responses with hide_disabled_flags both enabled and disabled:

# Get all flags
curl -s -L -H "X-Environment-Key: ser.xxx" \
  http://localhost:8000/api/v1/flags/ | jq

# Get identity flags
curl -s -L -X POST \
  -H "X-Environment-Key: ser.xxx" \
  -H "Content-Type: application/json" \
  -d '{"identifier": "test-user"}' \
  http://localhost:8000/api/v1/identities/ | jq