Initial commit: Hermes Chat v2

Svelte 5 + shadcn-svelte + Tailwind CSS v4 chat interface
for Hermes Agent with Monaco editor, file drag/drop,
artifacts, image preview, and real session management.

- SSE streaming via hermes CLI proxy
- File upload + drag/drop with image preview
- Code artifacts with Monaco editor
- Markdown + highlight.js syntax highlighting
- Full settings (model, provider, temp, system prompt)
- 12 shadcn UI components
- Dark/light theme

src/lib/components/ui/sheet/sheet-overlay.svelte

@@ -0,0 +1,26 @@
+<script lang="ts">
+	import { Dialog as SheetPrimitive } from "bits-ui";
+	import { cn } from "$lib/utils.ts";
+
+	let {
+		class: className = "",
+		children,
+		...restProps
+	}: {
+		class?: string;
+		children?: import("svelte").Snippet;
+		[key: string]: unknown;
+	} = $props();
+</script>
+
+<SheetPrimitive.Overlay
+	class={cn(
+		"fixed inset-0 z-50 bg-black/80 data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0",
+		className
+	)}
+	{...restProps}
+>
+	{#if children}
+		{@render children()}
+	{/if}
+</SheetPrimitive.Overlay>