tune(reusable): claude-code=3 models x 5 lenses (claude was the bottleneck)

Bump the default provider_concurrency claude-code 1 -> 3 so all three claude
models run concurrently (each already runs its 5 lenses at once). Peak is now
3 x 5 = 15 concurrent claude -p per pass. Claude was the wall-clock bottleneck
running serially; subscription is expected to handle the concurrency.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -48,7 +48,7 @@ Dockerfile             multi-stage; private-module creds via BuildKit secrets ne
 .gitea/workflows/build-image.yml   push main → :latest; tag v* → :<tag>+:latest; PR → build-only
 .gitea/workflows/review-reusable.yml  reusable (workflow_call) review job; ships the DEFAULT swarm as
                        input defaults (3 cloud + Claude Code sonnet/opus/opus:max, 5-lens suite;
-                       claude models serial, 5 lenses each) so consumers inherit it by omitting `with:`. Consumers subscribe
+                       3 claude models concurrent, 5 lenses each) so consumers inherit it by omitting `with:`. Consumers subscribe
                        with an ~8-line caller forwarding only the secrets the reviewer needs (Phase 4);
                        gadfly's own adversarial-review.yml is a thin caller of it (dogfoods the path).
 examples/              copy-paste consumer stub workflows for different providers