ci: skip docs-only triggers; document per-stage local-ci gate

ui-test workflow gains a `!**/*.md` negation so commits touching only
markdown (READMEs, PLAN.md updates, topic docs) no longer kick off the
full Go + Vitest + Playwright pipeline. Mixed commits keep triggering
because at least one positive path (`ui/**`, `gateway/**`, …) still
matches.

Project CLAUDE.md adds a per-stage CI gate section so the local
Gitea Actions runner is exercised at the close of every stage from
any PLAN.md, with the push step pre-authorised.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.gitea/workflows/ui-test.yaml

@@ -19,6 +19,11 @@ on:
       - 'go.work'
       - 'go.work.sum'
       - '.gitea/workflows/ui-test.yaml'
+      # Skip docs-only commits. Negation removes pure markdown changes;
+      # mixed commits (code + .md) still match a positive pattern above
+      # and trigger the workflow. Image and other binary asset paths
+      # are already outside the positive list.
+      - '!**/*.md'
   pull_request:
     paths:
       - 'ui/**'
@@ -29,6 +34,7 @@ on:
       - 'go.work'
       - 'go.work.sum'
       - '.gitea/workflows/ui-test.yaml'
+      - '!**/*.md'
 
 jobs:
   test: