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/hooks/useAppearance.test.ts

@@ -0,0 +1,165 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { applyTheme, applyFontSize, applyAccentColor, resolveTheme } from "./useAppearance";
+
+const windowMocks = vi.hoisted(() => ({
+    setTheme: vi.fn().mockResolvedValue(undefined),
+    setBackgroundColor: vi.fn().mockResolvedValue(undefined),
+}));
+
+vi.mock("@tauri-apps/api/window", () => ({
+    getCurrentWindow: () => ({
+        setTheme: windowMocks.setTheme,
+        setBackgroundColor: windowMocks.setBackgroundColor,
+    }),
+}));
+
+describe("useAppearance helpers", () => {
+    const getRoot = () => document.documentElement;
+
+    const stubMatchMedia = (
+        matches: boolean,
+        addEventListener: ReturnType<typeof vi.fn>,
+        removeEventListener: ReturnType<typeof vi.fn>,
+    ) => {
+        Object.defineProperty(window, "matchMedia", {
+            configurable: true,
+            writable: true,
+            value: vi.fn().mockReturnValue({
+                matches,
+                addEventListener,
+                removeEventListener,
+            }),
+        });
+    };
+
+    beforeEach(() => {
+        getRoot().classList.remove("light");
+        delete getRoot().dataset.fontSize;
+        getRoot().style.removeProperty("--color-accent");
+        windowMocks.setTheme.mockClear();
+        windowMocks.setBackgroundColor.mockClear();
+    });
+
+    afterEach(() => {
+        getRoot().classList.remove("light");
+        delete getRoot().dataset.fontSize;
+        getRoot().style.removeProperty("--color-accent");
+        delete (window as unknown as { matchMedia?: unknown }).matchMedia;
+    });
+
+    it('applyTheme("dark") removes the light class', () => {
+        getRoot().classList.add("light");
+        applyTheme("dark");
+        expect(getRoot().classList.contains("light")).toBe(false);
+    });
+
+    it('applyTheme("light") adds the light class', () => {
+        applyTheme("light");
+        expect(getRoot().classList.contains("light")).toBe(true);
+    });
+
+    it('applyTheme("system") keeps dark when the OS does not prefer light', () => {
+        const addEventListener = vi.fn();
+        const removeEventListener = vi.fn();
+        stubMatchMedia(false, addEventListener, removeEventListener);
+        const cleanup = applyTheme("system");
+        expect(getRoot().classList.contains("light")).toBe(false);
+        expect(addEventListener).toHaveBeenCalled();
+        cleanup();
+        expect(removeEventListener).toHaveBeenCalled();
+    });
+
+    it('applyTheme("system") adds the light class when the OS prefers light', () => {
+        stubMatchMedia(true, vi.fn(), vi.fn());
+        applyTheme("system");
+        expect(getRoot().classList.contains("light")).toBe(true);
+    });
+
+    describe("resolveTheme", () => {
+        it('resolveTheme("light") is "light"', () => {
+            expect(resolveTheme("light")).toBe("light");
+        });
+
+        it('resolveTheme("dark") is "dark"', () => {
+            expect(resolveTheme("dark")).toBe("dark");
+        });
+
+        it('resolveTheme("system") is "dark" when the OS does not prefer light', () => {
+            stubMatchMedia(false, vi.fn(), vi.fn());
+            expect(resolveTheme("system")).toBe("dark");
+        });
+
+        it('resolveTheme("system") is "light" when the OS prefers light', () => {
+            stubMatchMedia(true, vi.fn(), vi.fn());
+            expect(resolveTheme("system")).toBe("light");
+        });
+
+        it('resolveTheme("system") falls back to "dark" without matchMedia', () => {
+            delete (window as unknown as { matchMedia?: unknown }).matchMedia;
+            expect(resolveTheme("system")).toBe("dark");
+        });
+    });
+
+    it('applyFontSize("small") sets the data attribute', () => {
+        applyFontSize("small");
+        expect(getRoot().dataset.fontSize).toBe("small");
+    });
+
+    it('applyFontSize("large") sets the data attribute', () => {
+        applyFontSize("large");
+        expect(getRoot().dataset.fontSize).toBe("large");
+    });
+
+    it('applyFontSize("medium") removes the data attribute', () => {
+        getRoot().dataset.fontSize = "large";
+        applyFontSize("medium");
+        expect(getRoot().dataset.fontSize).toBeUndefined();
+    });
+
+    it('applyAccentColor sets the custom property for a valid hex', () => {
+        applyAccentColor("#22C55E");
+        expect(
+            getRoot().style.getPropertyValue("--color-accent").toLowerCase()
+        ).toBe("#22c55e");
+    });
+
+    it('applyAccentColor accepts lowercase hex', () => {
+        applyAccentColor("#2563eb");
+        expect(
+            getRoot().style.getPropertyValue("--color-accent").toLowerCase()
+        ).toBe("#2563eb");
+    });
+
+    it('applyAccentColor removes the custom property for an invalid value', () => {
+        getRoot().style.setProperty("--color-accent", "#22C55E");
+        applyAccentColor("blue");
+        expect(getRoot().style.getPropertyValue("--color-accent")).toBe("");
+    });
+
+    it('applyAccentColor rejects malformed hex', () => {
+        applyAccentColor("#22C5");
+        expect(getRoot().style.getPropertyValue("--color-accent")).toBe("");
+    });
+
+    it("syncs the native window (theme + background) for light", async () => {
+        applyTheme("light");
+        // Allow the fire-and-forget dynamic import + invoke to settle.
+        await new Promise((r) => setTimeout(r, 0));
+        expect(windowMocks.setTheme).toHaveBeenCalledWith("light");
+        expect(windowMocks.setBackgroundColor).toHaveBeenCalledWith("#FAFAFA");
+    });
+
+    it("syncs the native window (theme + background) for dark", async () => {
+        applyTheme("dark");
+        await new Promise((r) => setTimeout(r, 0));
+        expect(windowMocks.setTheme).toHaveBeenCalledWith("dark");
+        expect(windowMocks.setBackgroundColor).toHaveBeenCalledWith("#0A0A0B");
+    });
+
+    it("resets the window to follow the OS when switching to system", async () => {
+        stubMatchMedia(false, vi.fn(), vi.fn());
+        applyTheme("system");
+        await new Promise((r) => setTimeout(r, 0));
+        expect(windowMocks.setTheme).toHaveBeenCalledWith(null);
+    });
+});