Adding a server by hand offered no way to set custom HTTP headers, so the
only route to a cookie or a routing header was importing a config file.
The manual "Add server" form now carries a Custom Headers key/value editor
for the sse / streamable-http transports, pre-populated when editing or
cloning and submitted alongside the config.
Headers are not part of `MCPServerConfig` — they live on the entry's
`settings` — so they travel as `onSubmit`'s third argument rather than
folded into the config, and `addServer` / `updateServer` gained an optional
`settings` parameter to carry them to the backend (`POST /api/servers`
already accepted one). `updateServer`'s omission semantics are unchanged:
with no settings passed, the route still preserves the node on disk.
`KeyValueRows` moves out of ServerSettingsForm into a shared element so the
two editors cannot drift, and each row's controls gain a row-scoped
`aria-label` ("header value, Cookie", "Remove header, Cookie") — previously
every remove button announced only "X", indistinguishable across rows.
Signed-off-by: cliffhall <cliff@futurescale.com>