add original thought posting + fix all typecheck/test warnings
periodic musing system: process_musing() on agent, original_thought() on
handler, scheduled via thought_post_hours config, triggerable via
POST /api/control/post. agent can decline (action=ignore) if nothing's
interesting.
typecheck fixes: nullable client.me guards, cache typing, global narrowing,
Any vs any, CosmikConnection populate_by_name, conftest import path.
test fix: skip on ModelHTTPError for flaky API tests.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>