fix: prevent sidebar action menus from being cropped

Use viewport-constrained positioning for sidebar action menus and keep the auth warning test isolated from local models.json config so pre-commit verification is deterministic.

src/server/sessions/piSessionService.test.ts

@@ -632,7 +632,7 @@ describe("PiSessionService", () => {
   it("refreshes auth state and dedupes warnings when logout removes the current model's credentials", async () => {
     const hub = new CapturingSessionEventHub();
     const authStorage = AuthStorage.inMemory({ anthropic: { type: "api_key", key: "sk-test" } });
-    const modelRegistry = ModelRegistry.create(authStorage);
+    const modelRegistry = ModelRegistry.inMemory(authStorage);
     const model = modelRegistry.find("anthropic", "claude-3-5-sonnet-20241022");
     if (model === undefined) throw new Error("Expected Anthropic model fixture");
     const fake = fakeRuntime("auth-session", { model, modelRegistry });