fix(ci): library_test Mount arg + 4 web test selectors + forgot-pw catch

Five fixes in one commit, all from the U1+U2+U3 push:

1. internal/api/library_test.go's Mount call wasn't updated when
   U3-T4 added the mailer.Sender param. 17 args, sig wants 18.
   Adds a trailing nil for the mailer. Same shape of test-fixture
   lag the project has hit before — flagged as a recurring pattern
   for the DRY-pass slice.

2. web/src/routes/settings/settings.test.ts mocked $lib/api/me with
   `getAPIToken: vi.fn()` (no return value). The new /settings API
   Token card's $effect calls `getAPIToken().then(...)` which threw
   "Cannot read properties of undefined (reading 'then')" on every
   ListenBrainz test. Default the mock to mockResolvedValue so any
   test that doesn't override gets a valid resolution.

3. web/src/routes/admin/users/users.test.ts queried row buttons by
   /^Delete$/ but T3 added per-user aria-labels ("Delete alice"),
   so the row buttons' accessible name is no longer "Delete". The
   modal's confirm button has no aria-label so its name IS "Delete"
   exactly. Tests now click by per-user aria-label first, then by
   /^Delete$/ for the modal confirm.

4. Same file: /Set password/i regex matched both the dialog's
   submit button AND the row's "Reset password for ..." buttons
   (because regex `Set` matches "ReSet" case-insensitively). Switched
   to /^Set password$/ exact-match.

5. web/src/routes/reset-password/[token]/reset-password.test.ts had
   /New password/i which matched both the "New password" and
   "Confirm new password" labels. Switched to exact-match string
   selectors.

6. web/src/routes/forgot-password/+page.svelte's onSubmit handler
   had no catch — a rejected forgotPassword() bubbled as an
   unhandled rejection in vitest. Added a silent catch since the
   page intentionally shows the same success message regardless of
   outcome (no-enumeration posture).

web/src/routes/settings/settings.test.ts

@@ -14,7 +14,9 @@ vi.mock('$lib/api/listenbrainz', () => ({
 vi.mock('$lib/api/me', () => ({
   updateProfile: vi.fn(),
   changePassword: vi.fn(),
-  getAPIToken: vi.fn(),
+  // Default to a resolved value so the page's $effect doesn't crash
+  // on `.then()` of undefined when individual tests don't override.
+  getAPIToken: vi.fn().mockResolvedValue({ api_token: '' }),
   regenerateAPIToken: vi.fn()
 }));