refactor(scene): expose scene services via the lib interface, drop browser globals

[bofeng-song]

Problem

The scene editor and preview pages reached the scene services through ad-hoc browser globals (window.cli.Scene / window.cli.SceneEvents) and read their server address from another global (window.WebEnv). This is not a real interface, leaks globals, and cannot be shared with external IDEs that consume the src/lib layer. src/lib/cli.ts only re-exported types and had no importers.

window.cli.SceneEvents was also wired to messageManager (an isolated event emitter), while service events such as editor:open are emitted on ServiceEvents (a GlobalEventManager). Listeners registered on the former never fired.

Changes

ServiceManager — single typed entry

• Add init(serverURL), getServices(): IServiceManager and getServiceEvents(): GlobalEventManager. getServiceEvents() returns ServiceEvents, where service events are actually emitted (this also fixes the dead editor:open listener).

Public lib interface

• Delete the unused src/lib/cli.ts.
• Re-export Services (IServiceManager), IPublicServiceManager and GlobalEventManager from src/lib/scene/scene.ts, so external IDEs use Scene.Services / Scene.GlobalEventManager.

Drop browser globals; pass the address through the boot interface

• engine-bootstrap.ts: remove the globalThis.cli assignment; startup() calls serviceManager.init(serverURL).
• scene-editor-boot.js / game-boot.js: boot({ ip, port, https }) composes the server URL (falls back to location.origin) and returns a context { services, events, serverURL } from serviceManager.getServices() / getServiceEvents().
• engine-loader.js: takes serverURL as an argument (new exported composeServerURL) instead of reading window.WebEnv; editor-stub-preload.js becomes initEditorStub(serverURL).
• load-scene.js / preview-app.js: consume the boot context (services / events) instead of window.cli.*.
• scene-editor.ejs / preview.ejs / game.ejs: call boot({ ip, port, https }); the scene editor page uses the returned context via window.SceneCtx. Removed window.WebEnv.
• scene.scripting.middleware.ts / game-preview.middleware.ts: inject ip / port / https into the templates instead of a combined serverURL.
• main.ts (native scene worker): use serviceManager.init(...); the server URL still arrives via the --serverURL fork argument.

The engine-required window.CC_EDITOR / window.CC_PREVIEW flags and globalThis.cce.Script (used by the engine) are intentionally kept.

Test

• npx tsc -b passes.
• npm run build:static-web rebuilds the scene bundle: no globalThis.cli, and getServices / getServiceEvents are present.
• Scene editor (/scene-editor/), resource preview (/preview) and game preview (/) load; editor:open now fires; no window.cli / window.WebEnv remain in the served static assets.

[bofeng-song]

Consolidated into #745 (single optimization PR). Closing this one.