A plugin manifest's `config_schema` now reaches the Desktop: `plugins.manage list`
returns each plugin's schema with the current `plugins.entries.<id>.settings`
values (`settings_schema`), and a new `settings` action writes edits through
`hermes_cli.plugins_state.save_plugin_setting` — the writer extracted from
`PluginContext.set_config`, so the plugin, the CLI and the Desktop share one
config path, one lock and the same managed-install / managed-key refusals.
The Plugins tab grows a gear per plugin with a schema; the inline form is
table-driven (`FIELD_CONTROLS` / `INITIAL_TEXT` / `COERCE` keyed on the wire
field type) for string / number / boolean / enum / json / secret. Secrets are
declared with `type: secret`: the row carries only the `.env` name and a
presence flag, the client writes the value through the existing `PUT /api/env`
credential route, and the RPC refuses secret keys so nothing lands in
config.yaml.
Contracts regenerated; docs gain a "Settings form in the Desktop" section.
