Migrate to utoipa-axum and update to utoipa 5.4

[Copilot]

Migrates from utoipa with axum_extras feature to the dedicated utoipa-axum integration crate, addressing the deprecation path and enabling better compile-time route safety.

Dependency Changes

• Added utoipa-axum = "0.2.0"
• Updated utoipa from 5.3.1 to 5.4.0
• Removed axum_extras feature (deprecated integration path)

Server Implementation

• Replaced manual route registration with OpenApiRouter::with_openapi() and routes!() macro
• Each handler registered individually via separate routes!() calls to avoid method/path conflicts
• Removed context_path attributes from path annotations (handled by .nest() mounting)
• OpenAPI spec now extracted via .split_for_parts() instead of ::openapi() calls

Before:

let api_router = Router::new()
    .route("/health", get(health))
    .route("/v1/ned/tz/{lng}/{lat}", get(timezone_ned_v1));

Router::new()
    .merge(SwaggerUi::new("/swagger").url("/api-docs/openapi.json", ApiDoc::openapi()))
    .nest("/api", api_router)

After:

let (api_router, api) = OpenApiRouter::with_openapi(ApiDoc::openapi())
    .routes(routes!(health))
    .routes(routes!(timezone_ned_v1))
    .split_for_parts();

Router::new()
    .merge(SwaggerUi::new("/swagger").url("/api-docs/openapi.json", api))
    .nest("/api", api_router)

All existing API endpoints and tests remain unchanged.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Move to utoipa_axum, and bump key packages.</issue_title>
<issue_description></issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Move to utoipa_axum, and bump key packages. #10

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