feat(omo): improve agent model selection UX and fix lowercase keys (#1004)

* fix(omo): use lowercase keys for builtin agent definitions

OMO config schema expects all agent keys to be lowercase.
Updated OMO_BUILTIN_AGENTS keys (Sisyphus → sisyphus, Hephaestus →
hephaestus, etc.) and aligned Rust test fixtures accordingly.

* feat(omo): add i18n support and tooltips for agent/category descriptions

* feat(omo): add preset model variants for thinking level support

Add OPENCODE_PRESET_MODEL_VARIANTS constant with variant definitions
for Google, OpenAI, and Anthropic models. The omoModelVariantsMap
builder now falls back to presets when config-defined variants are
absent, enabling the variant selector for supported models.

* feat(omo): replace model select with searchable combobox and improve fallback handling

* feat(omo): enrich preset model defaults and metadata fallback

* fix(omo): preserve custom fields and align otherFields import/validation

* fix: resolve omo clippy warnings and include app update

src/App.tsx

@@ -141,7 +141,11 @@ function App() {
 
   // Fallback from sessions view when switching to an app without session support
   useEffect(() => {
-    if (currentView === "sessions" && activeApp !== "claude" && activeApp !== "codex") {
+    if (
+      currentView === "sessions" &&
+      activeApp !== "claude" &&
+      activeApp !== "codex"
+    ) {
       setCurrentView("providers");
     }
   }, [activeApp, currentView]);