✨ feat(server): /api/info aggregator + frontend version footer (#40)

Co-authored-by: Gabriel Radureau <arcodange@gmail.com>
Co-committed-by: Gabriel Radureau <arcodange@gmail.com>

features/info/info.feature

@@ -0,0 +1,38 @@
+# features/info/info.feature
+@info @critical
+Feature: Info Endpoint
+  The /api/info endpoint should return composite application information
+
+  @basic @critical
+  Scenario: GET /api/info returns all required fields
+    Given the server is running
+    When I request the info endpoint
+    Then the status code should be 200
+    And the response should be JSON
+    And the response should contain "version"
+    And the response should contain "commit_short"
+    And the response should contain "build_date"
+    And the response should contain "uptime_seconds"
+    And the response should contain "cache_enabled"
+    And the response should contain "healthz_status"
+    And the "healthz_status" field should equal "healthy"
+
+  @version @critical
+  Scenario: version field matches semantic version pattern
+    Given the server is running
+    When I request the info endpoint
+    Then the status code should be 200
+    And the "version" field should match /^\d+\.\d+\.\d+$/
+
+  @cache @skip @bdd-deferred
+  Scenario: /api/info is cached when cache is enabled
+    # Deferred: the BDD testsetup currently runs with cache disabled
+    # (see "Cache service disabled" in test logs). Cache HIT/MISS behavior
+    # is covered by unit tests on the cache service. Reopen this scenario
+    # if/when the BDD harness gains a cache-enabled mode (likely after
+    # ADR-0022 Phase 2).
+    Given the server is running with cache enabled
+    When I request the info endpoint
+    Then the response header "X-Cache" should be "MISS"
+    When I request the info endpoint again
+    Then the response header "X-Cache" should be "HIT"

features/info/info_test.go

@@ -0,0 +1,16 @@
+package info
+
+import (
+	"testing"
+
+	"dance-lessons-coach/pkg/bdd/testsetup"
+)
+
+func TestInfoBDD(t *testing.T) {
+	config := testsetup.NewFeatureConfig("info", "progress", false)
+	suite := testsetup.CreateTestSuite(t, config, "dance-lessons-coach BDD Tests - Info Feature")
+
+	if suite.Run() != 0 {
+		t.Fatal("non-zero status returned, failed to run info BDD tests")
+	}
+}