feat(docker): remove bundled Redis; use external host install

Compose stack is MySQL+Nexus only; wizard Redis check is non-blocking
and defaults to host.docker.internal for self-managed Redis.

Co-authored-by: Cursor <cursoragent@cursor.com>

server/api/install.py

@@ -116,14 +116,13 @@ def _docker_wizard_defaults() -> dict[str, str] | None:
     """Prefill install step 3 when running inside docker-compose.prod.yml."""
     if os.environ.get("NEXUS_DOCKER_WRITE_ENV") != "1" and not os.environ.get("REDIS_HOST"):
         return None
-    rh, rp, _ = _resolve_redis_probe()
     return {
         "db_host": os.environ.get("MYSQL_HOST", "mysql"),
         "db_port": os.environ.get("MYSQL_PORT", "3306"),
         "db_name": "nexus",
         "db_user": "nexus",
-        "redis_host": rh,
-        "redis_port": str(rp),
+        "redis_host": "host.docker.internal",
+        "redis_port": "6379",
         "redis_db": "0",
     }
 
@@ -443,9 +442,9 @@ async def env_check():
             "pass": False,
         })
 
-    # Redis — Docker Compose: redis:6379 (not published on host 127.0.0.1)
+    # Redis — 用户自行安装（1Panel/宿主机），不阻塞安装向导
     redis_ok = False
-    redis_msg = "未安装"
+    redis_msg = "未检测"
     rh, rp, rpass = _resolve_redis_probe()
     redis_label = f"{rh}:{rp}"
     try:
@@ -461,14 +460,14 @@ async def env_check():
             redis_ok = True
             redis_msg = f"✓ 已连接 {redis_label}"
         except Exception as e:
-            redis_msg = f"连接失败: {e}"
+            redis_msg = f"未连接 {redis_label}（可继续，步骤3配置或稍后安装 Redis）— {e}"
     except ImportError:
-        redis_msg = "redis 库未安装"
+        redis_msg = "redis 库未安装（可继续）"
     checks.append({
         "name": "Redis",
-        "required": "已连接",
+        "required": "自行安装（步骤3配置）",
         "current": redis_msg,
-        "pass": redis_ok,
+        "pass": True,
     })
 
     # MySQL database — user configures in step 3