Remove federation functionality and related tests

- Deleted the `federation.rs` module and its associated functionality for federating thoughts to followers.
- Removed the `well_known.rs` module and its WebFinger discovery functionality.
- Eliminated references to federation in the `thought.rs` router and removed the spawning of background tasks for federating thoughts.
- Deleted tests related to WebFinger and user inbox interactions in `activitypub.rs`.
- Updated `Cargo.toml` to remove the `activitypub_federation` dependency.

thoughts-backend/api/src/routers/mod.rs

@@ -9,9 +9,8 @@ pub mod search;
 pub mod tag;
 pub mod thought;
 pub mod user;
-pub mod well_known;
 
-use crate::routers::{auth::create_auth_router, well_known::create_well_known_router};
+use crate::routers::auth::create_auth_router;
 use app::state::AppState;
 use root::create_root_router;
 use tower_http::cors::CorsLayer;
@@ -24,7 +23,6 @@ pub fn create_router(state: AppState) -> Router {
 
     Router::new()
         .merge(create_root_router())
-        .nest("/.well-known", create_well_known_router())
         .nest("/auth", create_auth_router())
         .nest("/users", create_user_router())
         .nest("/thoughts", create_thought_router())