rebrand: Switchboard Core → Armature

- Rename Go module switchboard-core → armature (155+ files)
- Rename Docker image → gobha/armature
- Rename K8s resources, secrets, deployments
- Rename Prometheus metrics switchboard_* → armature_*
- Rename env vars SWITCHBOARD_ADMIN_* → ARMATURE_ADMIN_*
- Rename DB names switchboard_core* → armature*
- Update all frontend branding, notification templates, docs
- Update CI scripts, e2e tests, Keycloak realm, nginx conf
- Rename scripts/switchboard-ca.sh → scripts/armature-ca.sh
- Rename k8s/switchboard.yaml → k8s/armature.yaml
- Rename chart alerting/dashboard files
- Fix: DockerHub push uses env: binding for secret injection
- Helm chart updated (name, labels, template functions, dashboard, alerting)
- Replace favicon/icon assets with Armature brand

No functional changes. Pure mechanical rename + CI fix.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/webhook/webhook.go

@@ -20,7 +20,7 @@ import (
 const (
 	maxAttempts    = 3
 	timeout        = 10 * time.Second
-	signatureHeader = "X-Switchboard-Signature"
+	signatureHeader = "X-Armature-Signature"
 )
 
 // Payload is the JSON body sent to webhook endpoints.
@@ -69,7 +69,7 @@ func Deliver(url, secret string, payload Payload) error {
 			return fmt.Errorf("webhook request build: %w", err)
 		}
 		req.Header.Set("Content-Type", "application/json")
-		req.Header.Set("User-Agent", "Switchboard-Webhook/1.0")
+		req.Header.Set("User-Agent", "Armature-Webhook/1.0")
 		if signature != "" {
 			req.Header.Set(signatureHeader, signature)
 		}