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/lib/dbCapabilities.ts

@@ -0,0 +1,46 @@
+import type { DbType } from "./types";
+
+export interface DbCapabilities {
+  /** Table browser + data grid. */
+  explorer: boolean;
+  /** SQL editor + history/saved. */
+  queries: boolean;
+  /** Functions/triggers/sequences/enums/extensions. */
+  objects: boolean;
+  /** ER schema diagram. */
+  visualizer: boolean;
+  /** Backup / restore / sync. */
+  tools: boolean;
+  /** Inline cell edits + changes queue. */
+  editing: boolean;
+  /** CSV/JSON import. */
+  import: boolean;
+  /** Copy table schema (DDL). */
+  ddl: boolean;
+  /** Create / edit / drop PostgreSQL objects via the changes queue. */
+  objectCrud: boolean;
+  /** Table maintenance (VACUUM/ANALYZE/REINDEX) + rebuild-table. */
+  maintenance: boolean;
+  /** Role browsing/management. */
+  roles: boolean;
+  /** Rebuild-table (rewrite in place) support. */
+  tableManagement: boolean;
+}
+
+const ALL_FALSE: DbCapabilities = {
+  explorer: false, queries: false, objects: false, visualizer: false,
+  tools: false, editing: false, import: false, ddl: false, objectCrud: false,
+  maintenance: false, roles: false, tableManagement: false,
+};
+
+export const DB_CAPABILITIES: Record<DbType, DbCapabilities> = {
+  postgresql: { ...ALL_FALSE, explorer: true, queries: true, objects: true, visualizer: true, tools: true, editing: true, import: true, ddl: true, objectCrud: true, maintenance: true, roles: true, tableManagement: true },
+  mysql:      { ...ALL_FALSE, explorer: true, queries: true, editing: true, import: true, ddl: true, tools: true },
+  sqlite:     { ...ALL_FALSE, explorer: true, queries: true, visualizer: true, editing: true, import: true, ddl: true, tools: true, tableManagement: true },
+  redis:      { ...ALL_FALSE },
+};
+
+/** Safe accessor — unknown types get the all-false capability set. */
+export function getCapabilities(dbType: string): DbCapabilities {
+  return (DB_CAPABILITIES as Record<string, DbCapabilities>)[dbType] ?? ALL_FALSE;
+}