feat(initial): scaffold @push.rocks/smartchat with core, CLI, and web layers

Three-layer architecture built on @push.rocks/smartagent:
- ts/ — ChatSession wrapping runAgent() with conversation state management
- ts_cli/ — ink-based terminal chat TUI (React.createElement, no JSX)
- ts_web/ — Lit web components (smartchat-window, smartchat-message, smartchat-input)

ts_web/plugins.ts

@@ -0,0 +1,10 @@
+// Lit
+import { LitElement, html, css } from 'lit';
+export { LitElement, html, css };
+export type { TemplateResult, CSSResult } from 'lit';
+
+// Core (cross-folder import)
+import { ChatSession } from '../ts/smartchat.classes.chatsession.js';
+export { ChatSession };
+export type { IChatSessionOptions, IChatCallbacks, IChatUsage } from '../ts/smartchat.interfaces.js';
+export type { IAgentRunResult } from '@push.rocks/smartagent';