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/settings.rs

@@ -0,0 +1,152 @@
+use crate::models::Settings;
+use crate::store::Store;
+use std::collections::HashMap;
+use std::sync::Mutex;
+
+pub fn get_settings_inner(state: &Mutex<Store>) -> Result<Settings, String> {
+    let store = state.lock().map_err(|e| e.to_string())?;
+    store.get_settings()
+}
+
+pub fn update_setting_inner(state: &Mutex<Store>, key: &str, value: &str) -> Result<(), String> {
+    let store = state.lock().map_err(|e| e.to_string())?;
+    store.update_setting(key, value)
+}
+
+#[tauri::command]
+pub fn get_settings(state: tauri::State<crate::AppState>) -> Result<Settings, String> {
+    get_settings_inner(&state.db_store)
+}
+
+#[tauri::command]
+pub fn update_setting(
+    state: tauri::State<crate::AppState>,
+    key: String,
+    value: String,
+) -> Result<(), String> {
+    update_setting_inner(&state.db_store, &key, &value)
+}
+
+// ---------------------------------------------------------------------------
+// Settings export / import (v0.7.8)
+// ---------------------------------------------------------------------------
+
+/// Flatten a `Settings` struct into the store's key/value map. Keys and value
+/// formats must round-trip through `Store::get_settings` (e.g. a `None`
+/// `default_folder_id` is stored as the literal `"null"` sentinel, which
+/// `get_settings` filters back to `None`).
+fn settings_to_kv(s: &crate::models::Settings) -> HashMap<String, String> {
+    let mut m = HashMap::new();
+    m.insert("confirm_before_delete".into(), s.confirm_before_delete.to_string());
+    if let Some(f) = &s.default_folder_id {
+        m.insert("default_folder_id".into(), f.clone());
+    } else {
+        m.insert("default_folder_id".into(), "null".into());
+    }
+    m.insert("theme".into(), s.theme.clone());
+    m.insert("font_size".into(), s.font_size.clone());
+    m.insert("accent_color".into(), s.accent_color.clone());
+    m.insert("table_refresh_rate".into(), s.table_refresh_rate.to_string());
+    m.insert("table_page_size".into(), s.table_page_size.to_string());
+    m.insert("editor_font_size".into(), s.editor_font_size.to_string());
+    m.insert("editor_font_family".into(), s.editor_font_family.clone());
+    m.insert("editor_word_wrap".into(), s.editor_word_wrap.clone());
+    m.insert("editor_minimap".into(), s.editor_minimap.to_string());
+    m.insert("editor_tab_size".into(), s.editor_tab_size.to_string());
+    if let Some(o) = &s.tag_order {
+        m.insert("tag_order".into(), o.clone());
+    }
+    m.insert(
+        "default_ports".into(),
+        serde_json::to_string(&s.default_ports).unwrap_or_default(),
+    );
+    m.insert(
+        "shortcuts".into(),
+        serde_json::to_string(&s.shortcuts).unwrap_or_default(),
+    );
+    m
+}
+
+#[tauri::command]
+pub fn export_settings(state: tauri::State<crate::AppState>) -> Result<String, String> {
+    let s = get_settings_inner(&state.db_store)?;
+    serde_json::to_string(&crate::models::settings::SettingsExport {
+        schema_version: 1,
+        settings: s,
+    })
+    .map_err(|e| e.to_string())
+}
+
+#[tauri::command]
+pub fn import_settings(
+    json: String,
+    state: tauri::State<crate::AppState>,
+) -> Result<(), String> {
+    let env: crate::models::settings::SettingsExport =
+        serde_json::from_str(&json).map_err(|e| format!("invalid settings file: {e}"))?;
+    let map = settings_to_kv(&env.settings);
+    let store = state.db_store.lock().map_err(|e| e.to_string())?;
+    store.apply_settings(&map)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::store::Store;
+
+    fn state() -> std::sync::Mutex<Store> {
+        let conn = rusqlite::Connection::open_in_memory().unwrap();
+        crate::store::migrations::run_migrations(&conn).unwrap();
+        std::sync::Mutex::new(Store::from_connection(conn))
+    }
+
+    #[test]
+    fn get_settings_returns_defaults() {
+        let st = state();
+        let s = get_settings_inner(&st).unwrap();
+        assert_eq!(s.theme, "system");
+        assert_eq!(s.font_size, "medium");
+        assert_eq!(s.accent_color, "#2563EB");
+    }
+
+    #[test]
+    fn update_setting_persists() {
+        let st = state();
+        update_setting_inner(&st, "theme", "light").unwrap();
+        assert_eq!(get_settings_inner(&st).unwrap().theme, "light");
+    }
+
+    #[test]
+    fn update_accent_color_persists() {
+        let st = state();
+        update_setting_inner(&st, "accent_color", "#EF4444").unwrap();
+        assert_eq!(get_settings_inner(&st).unwrap().accent_color, "#EF4444");
+    }
+
+    #[test]
+    fn settings_export_envelope_camel_case() {
+        use std::collections::HashMap;
+        let env = crate::models::settings::SettingsExport { schema_version: 1, settings: crate::models::Settings {
+            confirm_before_delete: true, default_folder_id: None, theme: "dark".into(), font_size: "medium".into(),
+            default_ports: HashMap::new(), tag_order: None, table_refresh_rate: 5, table_page_size: 50,
+            shortcuts: HashMap::new(), accent_color: "#2563EB".into(), editor_font_size: 14,
+            editor_font_family: "Menlo".into(), editor_word_wrap: "off".into(), editor_minimap: true, editor_tab_size: 2,
+        }};
+        let json = serde_json::to_string(&env).unwrap();
+        assert!(json.contains("\"schemaVersion\":1"));
+        assert!(json.contains("\"settings\":"));
+    }
+
+    #[test]
+    fn store_apply_settings_writes_all_keys() {
+        let conn = rusqlite::Connection::open_in_memory().unwrap();
+        crate::store::migrations::run_migrations(&conn).unwrap();
+        let store = crate::store::Store::from_connection(conn);
+        let mut map = std::collections::HashMap::new();
+        map.insert("theme".to_string(), "light".to_string());
+        map.insert("accent_color".to_string(), "#EF4444".to_string());
+        store.apply_settings(&map).unwrap();
+        assert_eq!(store.get_settings().unwrap().theme, "light");
+        assert_eq!(store.get_settings().unwrap().accent_color, "#EF4444");
+    }
+}