feat(plugin): surface loaded plugin commands in command-line autocomplete

Autocomplete suggestions came only from all_registered_command_names() —
the compile-time inventory registry returning &'static str — so
runtime-loaded plugin commands could never appear. Typing a plugin's
command prefix (e.g. `LS_`) showed nothing even with the plugin loaded
and its ribbon tab active; dispatch worked, only discovery was blind.

Collect each enabled plugin's ribbon ToolDef command ids plus its
manifest command_prefixes into a dynamic candidate pool
(OwnedRibbonGroup::command_ids → PluginManager::command_names →
plugin_command_names), refreshed in rebuild_ribbon_modules on startup
load, settings reload, and every enable/disable toggle. ranked_matches
now merges this pool with the static registry and returns owned strings.

A plugin.toml `commands = [...]` list for sub-verbs with no ribbon button
(e.g. LS_AUTOLABEL) stays a follow-up — it's a plugin-API surface change.

Closes #272

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/plugin/mod.rs

@@ -7,7 +7,7 @@ pub mod host;
 pub mod marketplace;
 pub mod registry;
 
-pub use registry::{all_ribbon_modules, ribbon_modules_enabled};
+pub use registry::{all_ribbon_modules, plugin_command_names, ribbon_modules_enabled};
 pub(crate) use registry::try_dispatch;
 
 /// Run a plugin entry point under a panic guard so a buggy external plugin

src/plugin/registry.rs

@@ -31,6 +31,24 @@ pub fn ribbon_modules_enabled(
     core
 }
 
+/// Command names contributed by loaded external plugins whose id is **not** in
+/// `disabled` — every ribbon tool's command id plus manifest command prefixes.
+/// The host merges these into command-line autocomplete so plugin commands are
+/// discoverable by typing, not only via ribbon buttons (#272).
+pub fn plugin_command_names(disabled: &rustc_hash::FxHashSet<String>) -> Vec<String> {
+    #[cfg(not(target_arch = "wasm32"))]
+    {
+        return crate::plugin::external::with_manager(|manager| {
+            manager.command_names(|id| disabled.contains(id))
+        });
+    }
+    #[cfg(target_arch = "wasm32")]
+    {
+        let _ = disabled;
+        Vec::new()
+    }
+}
+
 /// Dispatch `cmd` to a loaded external plugin (skipping disabled ones).
 /// Returns true if one handled it.
 pub(crate) fn try_dispatch(app: &mut OpenCADStudio, tab: usize, cmd: &str) -> bool {