Remove list_sibling_containers, which nothing called

It listed every container on the daemon — including the user's unrelated
postgres, mysql and other work — and handed the summaries to the webview.
It had a registration, a command, a docker-layer helper, a typed frontend
wrapper and a `SiblingContainer` type, and zero call sites.

An audit named it as step one of an escalation chain: enumerate the
daemon's containers, then point `update_project`'s unvalidated
`container_id` at one and read its files through the file-command
surface. The second half of that chain is closed now, but a command that
exposes the user's unrelated containers and serves no feature is surface
with no upside.

Found by the registration test added in the previous commit, which is the
answer to "why test something the compiler already checks": the compiler
is perfectly happy with a command nobody calls.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GBq2rGum6GX7xXgsas1fDc

app/src/lib/tauri-commands.ts

@@ -1,5 +1,5 @@
 import { invoke } from "@tauri-apps/api/core";
-import type { Project, ProjectPath, ContainerInfo, SiblingContainer, AppSettings, UpdateInfo, ImageUpdateInfo, FileEntry, FileContents, WebTerminalInfo, SttStatus, GatewayStatus, InstallOptions, ClaudeSession, ContainerCapabilities, ScheduledTask, ScheduledTaskInput, SchedulerNotification, AuthBridgeStatus, BrowserViewStatus, BrowserViewPopoutState, BrowserPageState, PlaywrightDetection, BrowserSetupOutcome, BrowserInstallTarget, ContainerStaleness, MigrationOptions, MigrationReport, MigrationState, ClearTokenOutcome, CaCertInfo } from "./types";
+import type { Project, ProjectPath, ContainerInfo, AppSettings, UpdateInfo, ImageUpdateInfo, FileEntry, FileContents, WebTerminalInfo, SttStatus, GatewayStatus, InstallOptions, ClaudeSession, ContainerCapabilities, ScheduledTask, ScheduledTaskInput, SchedulerNotification, AuthBridgeStatus, BrowserViewStatus, BrowserViewPopoutState, BrowserPageState, PlaywrightDetection, BrowserSetupOutcome, BrowserInstallTarget, ContainerStaleness, MigrationOptions, MigrationReport, MigrationState, ClearTokenOutcome, CaCertInfo } from "./types";
 
 // Docker
 export const checkDocker = () => invoke<boolean>("check_docker");
@@ -7,8 +7,6 @@ export const checkImageExists = () => invoke<boolean>("check_image_exists");
 export const buildImage = () => invoke<void>("build_image");
 export const getContainerInfo = (projectId: string) =>
   invoke<ContainerInfo | null>("get_container_info", { projectId });
-export const listSiblingContainers = () =>
-  invoke<SiblingContainer[]>("list_sibling_containers");
 
 // Projects
 export const listProjects = () => invoke<Project[]>("list_projects");

app/src/lib/types.ts

@@ -193,13 +193,6 @@ export interface ContainerInfo {
   image: string;
 }
 
-export interface SiblingContainer {
-  id: string;
-  names: string[] | null;
-  image: string;
-  state: string;
-  status: string;
-}
 
 export interface TerminalSession {
   id: string;