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>

ci/keycloak-realm.json

@@ -1,5 +1,5 @@
 {
-  "realm": "switchboard",
+  "realm": "armature",
   "enabled": true,
   "registrationAllowed": false,
   "loginWithEmailAllowed": true,
@@ -9,11 +9,11 @@
     "realm": [
       {
         "name": "sb-admin",
-        "description": "Switchboard admin role"
+        "description": "Armature admin role"
       },
       {
         "name": "sb-user",
-        "description": "Switchboard regular user role"
+        "description": "Armature regular user role"
       }
     ]
   },
@@ -29,11 +29,11 @@
   ],
   "clients": [
     {
-      "clientId": "switchboard",
-      "name": "Switchboard Core",
+      "clientId": "armature",
+      "name": "Armature",
       "enabled": true,
       "publicClient": false,
-      "secret": "switchboard-secret",
+      "secret": "armature-secret",
       "redirectUris": [
         "http://localhost:3000/*",
         "http://localhost:8080/*"
@@ -69,7 +69,7 @@
   "users": [
     {
       "username": "alice",
-      "email": "alice@switchboard.test",
+      "email": "alice@armature.test",
       "firstName": "Alice",
       "lastName": "Engineer",
       "enabled": true,
@@ -83,7 +83,7 @@
       ],
       "realmRoles": [
         "sb-user",
-        "default-roles-switchboard"
+        "default-roles-armature"
       ],
       "groups": [
         "/engineering"
@@ -91,7 +91,7 @@
     },
     {
       "username": "bob",
-      "email": "bob@switchboard.test",
+      "email": "bob@armature.test",
       "firstName": "Bob",
       "lastName": "Lead",
       "enabled": true,
@@ -106,7 +106,7 @@
       "realmRoles": [
         "sb-admin",
         "sb-user",
-        "default-roles-switchboard"
+        "default-roles-armature"
       ],
       "groups": [
         "/engineering",