Only the CLI could install a plugin at an exact commit (`--ref <sha>`); the
Desktop "Install from Git" dialog, the TUI gateway `plugins.manage install`
method and the dashboard `/agent-plugins/install` endpoint all called
`_install_plugin_core` without a ref, so a team that wanted everyone on the
same private-plugin commit had to leave the app for a terminal.
- `dashboard_install_plugin(ref=)` threads the pin to `_install_plugin_core`;
the 40-hex validation and HEAD verification are unchanged. The gateway
method and dashboard body accept `ref`.
- Desktop dialog gains an optional "Pin to commit" field (custom sources only,
client-side 40-hex check disables Install on anything shorter).
- `plugins.manage list` rows carry `pinned_sha`; the Desktop plugins tab shows
a `pinned @ <sha8>` badge and `hermes plugins list` prints `git pinned@<sha8>`
in Source, so a team can eyeball that everyone runs the same commit.
Teknium
6d89c1afde