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-tauri/src/commands/maintenance.test.rs

@@ -0,0 +1,28 @@
+use crate::db::pool::{ConnectionPoolManager, DbHandle};
+
+/// Connect directly via tokio-postgres (no tunnel) so tests are Tauri-free.
+async fn pool() -> (tokio::sync::Mutex<ConnectionPoolManager>, String) {
+    let h = std::env::var("GRIDLINE_TEST_PG_HOST").expect("set GRIDLINE_TEST_PG_HOST");
+    let p: u16 = std::env::var("GRIDLINE_TEST_PG_PORT").unwrap_or_else(|_| "5432".into()).parse().unwrap();
+    let u = std::env::var("GRIDLINE_TEST_PG_USER").expect("set GRIDLINE_TEST_PG_USER");
+    let d = std::env::var("GRIDLINE_TEST_PG_DB").expect("set GRIDLINE_TEST_PG_DB");
+    let pw = std::env::var("GRIDLINE_TEST_PG_PASSWORD").unwrap_or_default();
+    let (client, conn) = tokio_postgres::connect(
+        &format!("host={h} port={p} user={u} dbname={d} password={pw}"),
+        tokio_postgres::NoTls,
+    ).await.expect("connect to test PG");
+    let handle = tokio::spawn(async move { let _ = conn.await; });
+    let mut pm = ConnectionPoolManager::new();
+    let id = "test-conn".to_string();
+    pm.register(&id, DbHandle::Postgresql(client, handle));
+    (tokio::sync::Mutex::new(pm), id)
+}
+
+#[tokio::test]
+#[ignore]
+async fn run_maintenance_analyze_succeeds() {
+    let (pm, id) = pool().await;
+    let res = crate::commands::maintenance::run_maintenance_inner(&pm, &id, "public", "pg_type", "analyze").await.unwrap();
+    assert!(res.duration_ms >= 0);
+    assert!(res.message.to_lowercase().contains("analyze"));
+}