fix: migrations, auth, providers health check, E2E tests, remove neko-sama

- Add proper Alembic initial migration (0001_initial_schema.py)
- Migrate refresh tokens from JSON file to SQLite (RefreshTokenTable)
- Remove Neko-Sama provider entirely (redirects to Gupy, not a host)
- Fix provider health check always showing UNKNOWN
  - Run check_all_health() on startup
  - Fix POST /providers/health/check background task bug
  - Add HTMX refresh after manual health check trigger
- Fix anime search relevance scoring with MIN_RELEVANCE_THRESHOLD=0.5
- Replace bare 'except:' with 'except Exception:' across codebase
- Add Playwright E2E test suite (12 tests, auth setup, helpers)
- Fix toast container blocking clicks via pointer-events: none
- Remove obsolete Jest/Vite test files and config
- Clean up obsolete test_watchlist scripts
- Update sonarr model comment for active providers

tests/e2e/helpers.ts

@@ -0,0 +1,81 @@
+import { Page, expect } from '@playwright/test';
+
+export const TEST_USER = {
+  username: 'e2e_testuser',
+  password: 'TestPassword123!',
+};
+
+/**
+ * Log in via the UI login form.
+ */
+export async function login(page: Page, username: string, password: string) {
+  await page.goto('/login');
+  await page.fill('#loginUsername', username);
+  await page.fill('#loginPassword', password);
+
+  const [response] = await Promise.all([
+    page.waitForResponse((resp) => resp.url().includes('/api/auth/login')),
+    page.click('#loginSubmit'),
+  ]);
+
+  expect(response.status()).toBeLessThan(400);
+
+  // Wait for success message or redirect
+  await Promise.race([
+    page.locator('#authSuccess').waitFor({ state: 'visible', timeout: 5000 }),
+    page.waitForURL('**/web**', { timeout: 5000 }),
+  ]);
+}
+
+/**
+ * Register a new unique user via the UI form.
+ */
+export async function register(page: Page, username: string, password: string) {
+  await page.goto('/login');
+  await page.click('text=Inscription');
+
+  await page.fill('#registerUsername', username);
+  await page.fill('#registerPassword', password);
+  await page.fill('#registerPasswordConfirm', password);
+
+  const [response] = await Promise.all([
+    page.waitForResponse((resp) => resp.url().includes('/api/auth/register')),
+    page.click('#registerSubmit'),
+  ]);
+
+  expect(response.status()).toBeLessThan(400);
+
+  await page.locator('#authSuccess').waitFor({ state: 'visible', timeout: 5000 });
+}
+
+/**
+ * Switch to a tab by name (Accueil, Anime, Série, Watchlist, etc.)
+ */
+export async function switchTab(page: Page, tabName: string) {
+  // Wait for tabs to be rendered
+  await page.locator('nav#mainTabs .tab').first().waitFor({ state: 'visible', timeout: 5000 });
+  
+  const tab = page.locator('nav#mainTabs .tab', { hasText: new RegExp(tabName, 'i') });
+  await tab.waitFor({ state: 'visible', timeout: 5000 });
+  await tab.click();
+  await expect(tab).toHaveClass(/active/);
+}
+
+/**
+ * Wait for HTMX content to settle (no more hx-request in flight).
+ */
+export async function waitForHtmx(page: Page, timeout = 10000) {
+  await page.waitForFunction(
+    () => document.querySelectorAll('.htmx-request').length === 0,
+    { timeout }
+  );
+}
+
+/**
+ * Check that no unhandled JS errors occurred on the page.
+ */
+export function collectJsErrors(page: Page): string[] {
+  const errors: string[] = [];
+  page.on('pageerror', (err) => errors.push(err.message));
+  return errors;
+}