Let the /routines page accept a proposal, gated at step-up (#46)

Accepting a routine gives the trigger loop a new standing reason to speak to
the human, so it is the same authority tier as enabling a tool and shares the
stepUpOK gate; dismiss only ever makes maven quieter, so it is ungated.
Look at handleRoutines and acceptRoutine in cmd/mavweb/main.go: accept creates
the recurring reminder, then links it via the new ipc AcceptProposedRoutine.
The page now says what maven noticed in her own words (pattern.PhraseRoutine).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CGeSZxh1DCtRxmFVSYVGvJ

internal/auth/auth_test.go

@@ -446,6 +446,9 @@ func (r *recordingAPI) RevertFact(_ context.Context, _ string) (int64, error) {
 func (r *recordingAPI) ListProposedRoutines(_ context.Context) ([]ipc.ProposedRoutine, error) {
 	return nil, nil
 }
+func (r *recordingAPI) AcceptProposedRoutine(_ context.Context, _, _ int64) error {
+	return nil
+}
 func (r *recordingAPI) DismissProposedRoutine(_ context.Context, _ int64) error {
 	return nil
 }