refactor: convert to bun-workspaces monorepo (desktop/ + www/)

- Move the Tauri app (React frontend + Rust backend) into desktop/ via
  git mv — configs unchanged (relative paths: tauri.conf.json, vite.config.ts)
- Root package.json becomes a private bun workspace container with
  orchestration scripts; desktop package renamed gridline-desktop
- Scaffold www/ with Astro 7 + Tailwind v4 (hand-wired vite plugin,
  static output, ready for Dokploy)
- Update release.yml for the new layout: projectPath: desktop,
  desktop/src-tauri resource paths, rust-cache workspace path
- Update README + AGENTS.md structure trees and dev commands
- Verified: vitest (1074), cargo test (354), desktop build, tauri dev
  (window launches), tauri build (dmg + app bundles), Astro build

desktop/src/components/grid/CellContextMenu.tsx

@@ -0,0 +1,37 @@
+import { Copy, Braces, Pencil, CircleSlash, Link2, Eye, MousePointerClick } from "lucide-react";
+
+interface Props {
+  anchorRect: DOMRect;
+  editable: boolean;
+  isJson: boolean;
+  isFk: boolean;
+  nullable: boolean;
+  onCopy: () => void; onCopyJson: () => void; onEdit: () => void;
+  onSetNull: () => void; onOpenFk: () => void; onClose: () => void;
+  onViewRow: () => void; onSelectRow: () => void;
+}
+export function CellContextMenu({ anchorRect, editable, isJson, isFk, nullable, onCopy, onCopyJson, onEdit, onSetNull, onOpenFk, onClose, onViewRow, onSelectRow }: Props) {
+  const items: { label: string; icon: React.ReactNode; onClick: () => void; show: boolean }[] = [
+    { label: "Copy", icon: <Copy size={12} />, onClick: () => { onCopy(); onClose(); }, show: true },
+    { label: "Copy JSON", icon: <Braces size={12} />, onClick: () => { onCopyJson(); onClose(); }, show: isJson },
+    { label: "View Row", icon: <Eye size={12} />, onClick: () => { onViewRow(); onClose(); }, show: true },
+    { label: "Select Row", icon: <MousePointerClick size={12} />, onClick: () => { onSelectRow(); onClose(); }, show: true },
+    { label: "Edit", icon: <Pencil size={12} />, onClick: () => { onEdit(); onClose(); }, show: editable },
+    { label: "Set NULL", icon: <CircleSlash size={12} />, onClick: () => { onSetNull(); onClose(); }, show: editable && nullable },
+    { label: "Open FK reference", icon: <Link2 size={12} />, onClick: () => { onOpenFk(); onClose(); }, show: isFk },
+  ];
+  return (
+    <div
+      className="fixed z-50 min-w-[160px] bg-canvas border border-border rounded-md shadow-lg py-1 text-xs"
+      style={{ top: anchorRect.bottom, left: anchorRect.left }}
+      onClick={(e) => e.stopPropagation()}
+    >
+      {items.filter((i) => i.show).map((i) => (
+        <button key={i.label} onClick={i.onClick}
+          className="w-full flex items-center gap-2 px-3 py-1.5 hover:bg-surface text-left text-text">
+          {i.icon} {i.label}
+        </button>
+      ))}
+    </div>
+  );
+}