Add API documentation using scalar

Author: LostLuma

echo/Cargo.lock

@@ -15,6 +15,7 @@ reqwest = { version = "0.12.8", default-features = false, features = ["json", "n
 rocket = { version = "0.5.1", features = ["json"] }
 rocket-validation = "0.2.0"
 rocket_db_pools = { version = "0.2.0", features = ["sqlx_postgres"] }
+scalar-doc = "0.1.0"
 serde = "1.0.210"
 sqlx = { version = "0.7.4", features = ["chrono"] }
 tokio = "1.40.0"

echo/Cargo.toml

@@ -18,6 +18,7 @@ RUN --mount=type=cache,target=target \
     --mount=type=cache,target=/usr/local/cargo/registry \
     --mount=type=bind,source=Cargo.toml,target=Cargo.toml,readwrite \
     --mount=type=bind,source=Cargo.lock,target=Cargo.lock,readwrite \
+    --mount=type=bind,source=openapi.json,target=openapi.json,readwrite \
     # Use musl target as the binary is about 1MiB smaller
     cargo build --profile $PROFILE --target x86_64-unknown-linux-musl && \
     # The "dev" target directory is named "debug" instead