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

cmd/mavend/main.go

@@ -166,6 +166,9 @@ func (l *lockedAPI) ListProposedRoutines(ctx context.Context) ([]ipc.ProposedRou
 	return nil, errLocked
 }
 func (l *lockedAPI) DismissProposedRoutine(ctx context.Context, id int64) error { return errLocked }
+func (l *lockedAPI) AcceptProposedRoutine(ctx context.Context, id, remID int64) error {
+	return errLocked
+}
 func (l *lockedAPI) LookupTool(ctx context.Context, name string) (ipc.Tool, error) {
 	return ipc.Tool{}, errLocked
 }