DELETE /api/sessions/:id gains a force query param (#81). A forced kill
answers 200 with KillOutcome, naming what was retained and why; the
unforced kill keeps its 204. DaemonClient::kill_session takes the flag.
The crate held the wire types but not the wire surface, so every consumer
re-derived routes, URL construction and the error envelope.
Adds `routes` (path constants, axum patterns, and a single fallible
`ws_base`), the `ApiError` envelope, `DaemonInfo`, and a `DaemonClient`
behind an optional `client` feature. `SpawnPreset` moves here because it
rides `GET /api/info`; `maestro-config` re-exports it so the on-disk
schema and the payload stay one type.
`ws_base` now rejects a base with no recognised scheme. The five previous
copies disagreed — the CLI errored, the web proxy trusted it, the TUI
passed it through.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>