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>

Dockerfile.builder

@@ -1,5 +1,5 @@
 # ============================================
-# Switchboard Core — Builder Image
+# Armature — Builder Image
 # ============================================
 # Pre-caches Go modules and Node dependencies
 # for faster custom builds. Use as a base in
@@ -7,12 +7,12 @@
 # download on every build.
 #
 # Usage:
-#   FROM ghcr.io/switchboard-core/builder:latest AS go-builder
+#   FROM ghcr.io/armature/builder:latest AS go-builder
 #   COPY server/ /app/
-#   RUN cd /app && go build -o /bin/switchboard .
+#   RUN cd /app && go build -o /bin/armature .
 #
 # Or build this image locally:
-#   docker build -f Dockerfile.builder -t switchboard-builder .
+#   docker build -f Dockerfile.builder -t armature-builder .
 # ============================================
 
 # ── Go module cache ─────────────────────────
@@ -61,5 +61,5 @@ RUN ln -sf /usr/local/lib/node_modules/npm/bin/npm-cli.js /usr/local/bin/npm
 
 WORKDIR /build
 
-LABEL org.opencontainers.image.title="Switchboard Core Builder"
-LABEL org.opencontainers.image.description="Pre-cached build dependencies for faster custom Switchboard Core builds"
+LABEL org.opencontainers.image.title="Armature Builder"
+LABEL org.opencontainers.image.description="Pre-cached build dependencies for faster custom Armature builds"