test: add Playwright E2E test suite (30 tests)

Add browser-level end-to-end tests covering public pages, Keycloak
OAuth authentication flow, dashboard interactions, providers config,
developer section, organization pages, and sidebar navigation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

e2e/providers.spec.ts

@@ -0,0 +1,55 @@
+import { test, expect } from "@playwright/test";
+
+test.describe("Providers page", () => {
+  test.beforeEach(async ({ page }) => {
+    await page.goto("/providers");
+    await page.waitForSelector(".providers-page", { timeout: 15_000 });
+  });
+
+  test("providers page loads with header", async ({ page }) => {
+    await expect(page.locator(".page-header")).toContainText("Providers");
+  });
+
+  test("provider dropdown has Ollama selected by default", async ({
+    page,
+  }) => {
+    const providerSelect = page
+      .locator(".form-group")
+      .filter({ hasText: "Provider" })
+      .locator("select");
+
+    await expect(providerSelect).toHaveValue(/ollama/i);
+  });
+
+  test("changing provider updates the model dropdown", async ({ page }) => {
+    const providerSelect = page
+      .locator(".form-group")
+      .filter({ hasText: "Provider" })
+      .locator("select");
+
+    // Get current model options
+    const modelSelect = page
+      .locator(".form-group")
+      .filter({ hasText: /^Model/ })
+      .locator("select");
+    const initialOptions = await modelSelect.locator("option").allTextContents();
+
+    // Change to a different provider
+    await providerSelect.selectOption({ label: "OpenAI" });
+
+    // Wait for model list to update
+    await page.waitForTimeout(500);
+    const updatedOptions = await modelSelect.locator("option").allTextContents();
+
+    // Model options should differ between providers
+    expect(updatedOptions).not.toEqual(initialOptions);
+  });
+
+  test("save button shows confirmation feedback", async ({ page }) => {
+    const saveBtn = page.locator("button", { hasText: "Save Configuration" });
+    await saveBtn.click();
+
+    await expect(page.locator(".form-success")).toBeVisible({ timeout: 5_000 });
+    await expect(page.locator(".form-success")).toContainText("saved");
+  });
+});