refactor(swarm): one file per endpoint, matching existing router layout

Splits the three grouped router files into eight api_<verb>_<resource>.py
modules under decnet/web/router/swarm/ to match the convention used by
router/fleet/ and router/config/. Shared request/response models live in
_schemas.py. Keeps each endpoint easy to locate and modify without
stepping on siblings.

decnet/web/router/swarm/_schemas.py

@@ -0,0 +1,82 @@
+"""Request/response models shared across the swarm router endpoints."""
+from __future__ import annotations
+
+from datetime import datetime
+from typing import Any, Optional
+
+from pydantic import BaseModel, Field
+
+from decnet.config import DecnetConfig
+
+
+class EnrollRequest(BaseModel):
+    name: str = Field(..., min_length=1, max_length=128)
+    address: str = Field(..., description="IP or DNS the master uses to reach the worker")
+    agent_port: int = Field(default=8765, ge=1, le=65535)
+    sans: list[str] = Field(
+        default_factory=list,
+        description="Extra SANs (IPs / hostnames) to embed in the worker cert",
+    )
+    notes: Optional[str] = None
+
+
+class EnrolledBundle(BaseModel):
+    """Cert bundle returned to the operator — must be delivered to the worker."""
+
+    host_uuid: str
+    name: str
+    address: str
+    agent_port: int
+    fingerprint: str
+    ca_cert_pem: str
+    worker_cert_pem: str
+    worker_key_pem: str
+
+
+class SwarmHostView(BaseModel):
+    uuid: str
+    name: str
+    address: str
+    agent_port: int
+    status: str
+    last_heartbeat: Optional[datetime] = None
+    client_cert_fingerprint: str
+    enrolled_at: datetime
+    notes: Optional[str] = None
+
+
+class DeployRequest(BaseModel):
+    config: DecnetConfig
+    dry_run: bool = False
+    no_cache: bool = False
+
+
+class TeardownRequest(BaseModel):
+    host_uuid: str | None = Field(
+        default=None,
+        description="If set, tear down only this worker; otherwise tear down all hosts",
+    )
+    decky_id: str | None = None
+
+
+class HostResult(BaseModel):
+    host_uuid: str
+    host_name: str
+    ok: bool
+    detail: Any | None = None
+
+
+class DeployResponse(BaseModel):
+    results: list[HostResult]
+
+
+class HostHealth(BaseModel):
+    host_uuid: str
+    name: str
+    address: str
+    reachable: bool
+    detail: Any | None = None
+
+
+class CheckResponse(BaseModel):
+    results: list[HostHealth]