feat(agent): agent stream tunneling with TLS and dTLS (UDP) (#188)

* **New Features**
  * Multiplexed TLS port: HTTP API and a custom stream protocol can share one port via ALPN.
  * Agent-side TCP and DTLS/UDP stream tunneling with health-check support and runtime capability detection.
  * Agents now advertise per-agent stream support (TCP/UDP).

* **Documentation**
  * Added comprehensive stream protocol documentation.

* **Tests**
  * Extended integration and concurrency tests covering multiplexing, TCP/UDP streams, and health checks.

* **Chores**
  * Compose/template updated to expose both TCP and UDP ports.

internal/api/v1/docs/swagger.json

@@ -2356,6 +2356,16 @@
           "x-nullable": false,
           "x-omitempty": false
         },
+        "supports_tcp_stream": {
+          "type": "boolean",
+          "x-nullable": false,
+          "x-omitempty": false
+        },
+        "supports_udp_stream": {
+          "type": "boolean",
+          "x-nullable": false,
+          "x-omitempty": false
+        },
         "version": {
           "type": "string",
           "x-nullable": false,
@@ -2439,7 +2449,7 @@
       "type": "object",
       "properties": {
         "agent": {
-          "$ref": "#/definitions/Agent",
+          "$ref": "#/definitions/agentpool.Agent",
           "x-nullable": false,
           "x-omitempty": false
         },
@@ -4909,6 +4919,43 @@
       "x-nullable": false,
       "x-omitempty": false
     },
+    "agentpool.Agent": {
+      "type": "object",
+      "properties": {
+        "addr": {
+          "type": "string",
+          "x-nullable": false,
+          "x-omitempty": false
+        },
+        "name": {
+          "type": "string",
+          "x-nullable": false,
+          "x-omitempty": false
+        },
+        "runtime": {
+          "$ref": "#/definitions/agent.ContainerRuntime",
+          "x-nullable": false,
+          "x-omitempty": false
+        },
+        "supports_tcp_stream": {
+          "type": "boolean",
+          "x-nullable": false,
+          "x-omitempty": false
+        },
+        "supports_udp_stream": {
+          "type": "boolean",
+          "x-nullable": false,
+          "x-omitempty": false
+        },
+        "version": {
+          "type": "string",
+          "x-nullable": false,
+          "x-omitempty": false
+        }
+      },
+      "x-nullable": false,
+      "x-omitempty": false
+    },
     "auth.UserPassAuthCallbackRequest": {
       "type": "object",
       "properties": {

internal/api/v1/docs/swagger.yaml

@@ -8,6 +8,10 @@ definitions:
         type: string
       runtime:
         $ref: '#/definitions/agent.ContainerRuntime'
+      supports_tcp_stream:
+        type: boolean
+      supports_udp_stream:
+        type: boolean
       version:
         type: string
     type: object
@@ -48,7 +52,7 @@ definitions:
   Container:
     properties:
       agent:
-        $ref: '#/definitions/Agent'
+        $ref: '#/definitions/agentpool.Agent'
       aliases:
         items:
           type: string
@@ -1236,6 +1240,21 @@ definitions:
     x-enum-varnames:
     - ContainerRuntimeDocker
     - ContainerRuntimePodman
+  agentpool.Agent:
+    properties:
+      addr:
+        type: string
+      name:
+        type: string
+      runtime:
+        $ref: '#/definitions/agent.ContainerRuntime'
+      supports_tcp_stream:
+        type: boolean
+      supports_udp_stream:
+        type: boolean
+      version:
+        type: string
+    type: object
   auth.UserPassAuthCallbackRequest:
     properties:
       password: