build(deps): update shared-assets to v3.0.39

[UberMetroid]

Combines the shared-assets dependency updates represented by open PRs #16 and #17.

Changes:

• Updates shared-frontend and both direct shared-core declarations to v3.0.39.
• Regenerates Cargo.lock with one shared-core revision.
• Uses shared_frontend::i18n::Language in frontend/src/app/view.rs to match shared frontend component types.

Validation:

• cargo check --workspace
• cargo test --workspace