✨ feat(server): /api/info aggregator + frontend version footer

Sprint 2 of autonomous trainer day 2026-05-05. Mistral-implemented
through ICM workspace ship-info-aggregator (bootstrapped backend +
BDD before hitting price limit at stage 02), Claude-completed for
frontend + Playwright + verifier + PR.

Backend:
- GET /api/info aggregator returning version, commit_short, build_date,
  uptime_seconds, cache_enabled, healthz_status (single round trip)
- Optional cache via existing cache service (X-Cache: HIT/MISS)
- BDD scenario @critical covers happy path + version regex; cache
  scenario kept under @skip @bdd-deferred until BDD harness gains a
  cache-enabled mode

Frontend:
- AppFooterView (dumb) + AppFooter (smart wrapper, useFetch) following
  the HealthDashboard / HealthDashboardView pattern
- layouts/default.vue auto-applied via NuxtLayout in app.vue
- humaniseUptime helper in utils/
- Playwright tests use route.fulfill mocking (decoupled from dev-proxy
  infra), assert visible AND content (PR #32 lesson)

Docs:
- documentation/API.md /api/info entry with schema and rationale
- ADR-0026 documents composite endpoint vs separate calls choice

Verifier verdict (skill-driven, audit at stage 04): APPROVE_WITH_NITS.
Nits: handleInfo is 51 lines (could split into builder + emitter);
X-Cache: DISABLED could improve ops clarity.

Out-of-scope follow-up: existing tests/e2e/health.spec.ts happy path
hits the same dev-proxy infra issue as my footer happy path before
mocking. Same fix (server: false + route.fulfill) would apply.

pkg/bdd/steps/steps.go

@@ -89,6 +89,9 @@ func InitializeAllSteps(ctx *godog.ScenarioContext, client *testserver.Client, s
 	// Health steps
 	ctx.Step(`^I request the health endpoint$`, sc.healthSteps.iRequestTheHealthEndpoint)
 	ctx.Step(`^I request the healthz endpoint$`, sc.healthSteps.iRequestTheHealthzEndpoint)
+	ctx.Step(`^I request the info endpoint$`, sc.healthSteps.iRequestTheInfoEndpoint)
+	ctx.Step(`^I request the info endpoint again$`, sc.healthSteps.iRequestTheInfoEndpointAgain)
+	ctx.Step(`^the server is running with cache enabled$`, sc.healthSteps.theServerIsRunningWithCacheEnabled)
 	ctx.Step(`^the server is running$`, sc.healthSteps.theServerIsRunning)
 
 	// Auth steps
@@ -314,4 +317,8 @@ func InitializeAllSteps(ctx *godog.ScenarioContext, client *testserver.Client, s
 	ctx.Step(`^the status code should be (\d+)$`, sc.commonSteps.theStatusCodeShouldBe)
 	ctx.Step(`^the response should be JSON with fields "([^"]*)"$`, sc.commonSteps.theResponseShouldBeJSONWithFields)
 	ctx.Step(`^the "([^"]*)" field should equal "([^"]*)"$`, sc.commonSteps.theFieldShouldEqual)
+	ctx.Step(`^the "([^"]*)" field should match /([^/]+)/$`, sc.commonSteps.theFieldShouldMatch)
+	ctx.Step(`^the response should be JSON$`, sc.commonSteps.theResponseShouldBeJSON)
+	ctx.Step(`^the response should contain "([^"]*)"$`, sc.commonSteps.theResponseShouldContain)
+	ctx.Step(`^the response header "([^"]*)" should be "([^"]*)"$`, sc.commonSteps.theResponseHeader)
 }