feat: Companion agent download in ServerView + Gitea CI pipeline fix

Frontend:
- Add Companion Agent card to ServerView (status, download links, setup instructions)
- Shows agent connection status, last heartbeat, license key for copy
- Download buttons for Linux/Windows amd64 from Gitea releases

CI/CD:
- Fix build-companion.yml: replace actions/github-script with Gitea API curl
- Inject version from git tag via ldflags (-X main.version)
- Add VERSION variable to Makefile with ldflags injection
- Change main.go version from const to var for ldflags compatibility

Deployment:
- Add systemd service file (deployment/corrosion-companion.service)
- Add .gitignore for bin/ (binaries should come from CI, not repo)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/views/admin/ServerView.vue

@@ -1,6 +1,7 @@
 <script setup lang="ts">
-import { ref, onMounted } from 'vue'
+import { ref, computed, onMounted } from 'vue'
 import { useServerStore } from '@/stores/server'
+import { useAuthStore } from '@/stores/auth'
 import {
   Server,
   Wifi,
@@ -10,13 +11,62 @@ import {
   RotateCcw,
   Save,
   Loader2,
+  Download,
+  Terminal,
+  Monitor,
 } from 'lucide-vue-next'
 
 const server = useServerStore()
+const auth = useAuthStore()
 
 const editMode = ref(false)
 const saving = ref(false)
 const actionLoading = ref<string | null>(null)
+const copied = ref(false)
+
+const isAgentConnected = computed(() =>
+  server.connection?.connection_type === 'bare_metal' &&
+  server.connection?.connection_status === 'connected'
+)
+
+const agentLastSeen = computed(() => {
+  const ts = server.connection?.companion_last_seen
+  if (!ts) return null
+  return new Date(ts)
+})
+
+const agentLastSeenLabel = computed(() => {
+  const d = agentLastSeen.value
+  if (!d) return 'Never'
+  const diff = Math.floor((Date.now() - d.getTime()) / 1000)
+  if (diff < 60) return `${diff}s ago`
+  if (diff < 3600) return `${Math.floor(diff / 60)}m ago`
+  if (diff < 86400) return `${Math.floor(diff / 3600)}h ago`
+  return d.toLocaleDateString()
+})
+
+const licenseKey = computed(() => auth.license?.license_key || 'YOUR-LICENSE-KEY')
+
+const linuxCommands = computed(() => `# Download the agent
+curl -LO https://git.corrosionmgmt.com/vantzs/corrosion-admin-panel/releases/latest/download/corrosion-companion-linux-amd64
+chmod +x corrosion-companion-linux-amd64
+
+# Start with your license key
+export LICENSE_ID="${licenseKey.value}"
+export NATS_URL="nats://nats.corrosionmgmt.com:4222"
+export NATS_TOKEN="<your-nats-token>"
+export GAME_SERVER_PATH="/path/to/RustDedicated"
+./corrosion-companion-linux-amd64`)
+
+async function copyCommands() {
+  try {
+    await navigator.clipboard.writeText(linuxCommands.value)
+    copied.value = true
+    setTimeout(() => { copied.value = false }, 2000)
+  } catch {
+    // Clipboard API unavailable
+  }
+}
 
 const form = ref({
   server_name: '',
@@ -148,6 +198,101 @@ onMounted(async () => {
       </div>
     </div>
 
+    <!-- Companion Agent -->
+    <div class="bg-neutral-900 border border-neutral-800 rounded-lg p-5">
+      <div class="flex items-center gap-2 mb-5">
+        <Monitor class="w-4 h-4 text-oxide-400" />
+        <h2 class="text-sm font-medium text-neutral-400 uppercase tracking-wider">Companion Agent</h2>
+      </div>
+
+      <!-- Agent Status -->
+      <div class="grid grid-cols-2 lg:grid-cols-3 gap-6 mb-6">
+        <div>
+          <p class="text-xs text-neutral-500 mb-1">Agent Status</p>
+          <div class="flex items-center gap-2">
+            <span
+              class="w-2 h-2 rounded-full"
+              :class="isAgentConnected ? 'bg-green-400' : 'bg-neutral-600'"
+            />
+            <span
+              class="text-sm font-medium"
+              :class="isAgentConnected ? 'text-green-400' : 'text-neutral-400'"
+            >
+              {{ isAgentConnected ? 'Active' : 'Inactive' }}
+            </span>
+          </div>
+        </div>
+        <div>
+          <p class="text-xs text-neutral-500 mb-1">Connection Type</p>
+          <p class="text-sm font-medium text-neutral-100 uppercase">
+            {{ server.connection?.connection_type || '\u2014' }}
+          </p>
+        </div>
+        <div>
+          <p class="text-xs text-neutral-500 mb-1">Last Heartbeat</p>
+          <p class="text-sm font-medium" :class="agentLastSeen ? 'text-neutral-200' : 'text-neutral-500'">
+            {{ agentLastSeenLabel }}
+          </p>
+        </div>
+      </div>
+
+      <!-- Download Section -->
+      <div class="mb-6">
+        <div class="flex items-center gap-2 mb-3">
+          <Download class="w-3.5 h-3.5 text-neutral-500" />
+          <p class="text-xs font-medium text-neutral-400 uppercase tracking-wider">Download Companion Agent</p>
+        </div>
+        <div class="flex flex-wrap gap-3">
+          <a
+            href="https://git.corrosionmgmt.com/vantzs/corrosion-admin-panel/releases/latest/download/corrosion-companion-linux-amd64"
+            download="corrosion-companion-linux-amd64"
+            class="flex items-center gap-2 px-4 py-2.5 bg-neutral-800 hover:bg-neutral-700 text-neutral-200 border border-neutral-700 hover:border-neutral-600 rounded-lg text-sm font-medium transition-colors"
+          >
+            <Download class="w-4 h-4 text-oxide-400" />
+            Linux (amd64)
+          </a>
+          <a
+            href="https://git.corrosionmgmt.com/vantzs/corrosion-admin-panel/releases/latest/download/corrosion-companion-windows-amd64.exe"
+            download="corrosion-companion-windows-amd64.exe"
+            class="flex items-center gap-2 px-4 py-2.5 bg-neutral-800 hover:bg-neutral-700 text-neutral-200 border border-neutral-700 hover:border-neutral-600 rounded-lg text-sm font-medium transition-colors"
+          >
+            <Download class="w-4 h-4 text-oxide-400" />
+            Windows (amd64)
+          </a>
+        </div>
+      </div>
+
+      <!-- Quick Setup Section -->
+      <div>
+        <div class="flex items-center justify-between mb-3">
+          <div class="flex items-center gap-2">
+            <Terminal class="w-3.5 h-3.5 text-neutral-500" />
+            <p class="text-xs font-medium text-neutral-400 uppercase tracking-wider">Quick Setup (Linux)</p>
+          </div>
+          <button
+            @click="copyCommands"
+            class="flex items-center gap-1.5 px-3 py-1 text-xs font-medium rounded-md transition-colors"
+            :class="copied
+              ? 'bg-green-600/20 text-green-400 border border-green-600/30'
+              : 'bg-neutral-800 hover:bg-neutral-700 text-neutral-400 hover:text-neutral-200 border border-neutral-700'"
+          >
+            {{ copied ? 'Copied!' : 'Copy' }}
+          </button>
+        </div>
+        <div class="bg-black/50 border border-neutral-800 rounded-lg p-4 font-mono text-sm text-neutral-300 overflow-x-auto">
+          <p class="text-neutral-500"># Download the agent</p>
+          <p>curl -LO https://git.corrosionmgmt.com/vantzs/corrosion-admin-panel/releases/latest/download/corrosion-companion-linux-amd64</p>
+          <p>chmod +x corrosion-companion-linux-amd64</p>
+          <p class="mt-3 text-neutral-500"># Start with your license key</p>
+          <p>export LICENSE_ID=<span class="text-oxide-400">"{{ licenseKey }}"</span></p>
+          <p>export NATS_URL=<span class="text-oxide-400">"nats://nats.corrosionmgmt.com:4222"</span></p>
+          <p>export NATS_TOKEN=<span class="text-neutral-500">"&lt;your-nats-token&gt;"</span></p>
+          <p>export GAME_SERVER_PATH=<span class="text-neutral-500">"/path/to/RustDedicated"</span></p>
+          <p>./corrosion-companion-linux-amd64</p>
+        </div>
+      </div>
+    </div>
+
     <!-- Configuration -->
     <div class="bg-neutral-900 border border-neutral-800 rounded-lg p-5">
       <div class="flex items-center justify-between mb-4">