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/editor/SqlEditorField.tsx

@@ -0,0 +1,66 @@
+import { useCallback } from "react";
+import Editor, { type BeforeMount } from "@monaco-editor/react";
+import { useSettingsStore } from "../../stores/settingsStore";
+
+interface SqlEditorFieldProps {
+  value: string;
+  onChange: (value: string) => void;
+  height?: number;
+  readOnly?: boolean;
+}
+
+export function SqlEditorField({
+  value,
+  onChange,
+  height = 140,
+  readOnly = false,
+}: SqlEditorFieldProps) {
+  const editorFontFamily = useSettingsStore(
+    (s) => s.settings?.editor_font_family ?? "Space Mono",
+  );
+  const editorFontSize = useSettingsStore(
+    (s) => s.settings?.editor_font_size ?? 13,
+  );
+  const editorTabSize = useSettingsStore(
+    (s) => s.settings?.editor_tab_size ?? 4,
+  );
+
+  const handleBeforeMount: BeforeMount = useCallback((monaco) => {
+    monaco.editor.defineTheme("gridline-sql", {
+      base: "vs-dark",
+      inherit: true,
+      rules: [],
+      colors: {
+        "editor.background": "#00000000",
+        "editorGutter.background": "#00000000",
+        "editor.lineHighlightBackground": "#ffffff08",
+        "editorLineNumber.foreground": "#5b5b5e",
+        "editorLineNumber.activeForeground": "#a1a1a6",
+      },
+    });
+  }, []);
+
+  return (
+    <div className="h-full min-h-0" data-testid="sql-editor-field">
+      <Editor
+        height={height}
+        language="sql"
+        theme="gridline-sql"
+        beforeMount={handleBeforeMount}
+        value={value}
+        onChange={(v) => onChange(v ?? "")}
+        options={{
+          minimap: { enabled: false },
+          fontSize: editorFontSize,
+          fontFamily: editorFontFamily,
+          lineNumbers: "on",
+          scrollBeyondLastLine: false,
+          wordWrap: "on",
+          readOnly,
+          automaticLayout: true,
+          tabSize: editorTabSize,
+        }}
+      />
+    </div>
+  );
+}