share the forge and schedule wire types through swarm-controller-api

swarmctl hand-mirrored the controller's forge make-admin response and
the /api/schedules bodies. Both now import them from a new serde-only
crate, swarm-controller-api, the way hivectl and hive-c0re share
hive-host-sock. ToSchema sits behind its schema feature, which only
the controller turns on.

The wire format is unchanged: round-trip tests in the new crate pin
each type against the JSON the controller and swarmctl produced, and
the controller's OpenAPI document for these routes is byte-identical.

Files: swarm-controller-api/ is the new crate; swarm-controller and
swarmctl (src, Cargo.toml, Cargo.lock, root Cargo.toml) switch to it;
CLAUDE.md lists the crate and which swarmctl shapes are still local
mirrors; swarmctl/README.md says the forge and schedule bodies come
from the crate, so none of its lines still call them mirrored.

Part of #5472.

swarm-controller-api/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "swarm-controller-api"
+version.workspace = true
+edition.workspace = true
+readme = "README.md"
+
+[features]
+# `ToSchema` on every type, for swarm-controller, whose `OpenAPI` spec
+# describes them. Off by default so swarmctl does not link utoipa.
+schema = ["dep:utoipa"]
+
+[dependencies]
+serde.workspace = true
+utoipa = { workspace = true, optional = true }
+
+[dev-dependencies]
+serde_json.workspace = true
+
+[lints]
+workspace = true