Fix alpha9 pre-release audit findings: examples README link and timeout-sweep starvation backoff

Fixes two pre-release audit findings for 1.0.0-alpha9, plus a small repository-hygiene tweak. See #3608537.

• L2 (docs): the request-validation examples README linked the notification-delivery guide two directory levels up, but the README sits four levels below the module root, so the link resolved to a nonexistent path. Corrected to the module-root docs/.
• I1 (timeout sweep): for a due token whose effective definition could not be resolved (mid-edit, in-progress config import, or pruned pinned version), the sweep kept the passed deadline and moved on. Because the batch is bounded and deadline-sorted, such a token re-occupied a slot at the head of the batch every run and starved the due tokens behind it. The deferral the node-not-in-definition branch already performed is extracted into a shared deferDueToken() helper and used by the definition-unresolvable branch too, so both defer instead of one starving. Adds a kernel test replaying a due token whose definition was removed out from under it alongside a healthy due token.
• Repo hygiene: generalize .gitignore from AUDIT.md to AUDIT*.md.

No behavior change for correct configurations. Verified locally: phpcs clean, cspell clean, TimeoutTest kernel suite green (23 tests).