refactor: split services/docker.py into docker/ package

Split monolithic docker.py into focused modules:
- docker/compose.py — compose generation, execute_compose_command, volume sorting
- docker/container.py — container status, IP, logs, network, port finding
- docker/config_staging.py — instance dir, env file, config file staging
- docker/tunnel.py — cloudflared tunnel lifecycle (moved from services/tunnel.py)
- docker/__init__.py — re-exports all public symbols for backward compatibility
- services/tunnel.py — thin re-export wrapper for backward compatibility

Also includes schema extraction files created in prior work:
- schemas/config/config_profile.py
- schemas/project/*.py
- schemas/system/health.py
- schemas/tool/*.py
- schemas/user/*.py

All existing imports like 'from src.services.docker import X' and
'from src.services.tunnel import X' continue to work unchanged.

Quality gates: py_compile passed, ruff passed, import test passed.

apps/api/src/schemas/project/ssh_key.py

@@ -0,0 +1,36 @@
+"""SSH key request/response schemas."""
+
+import uuid
+from datetime import datetime
+
+from pydantic import BaseModel, ConfigDict
+
+
+class SSHKeyCreate(BaseModel):
+    name: str
+
+
+class SSHKeyResponse(BaseModel):
+    model_config = ConfigDict(from_attributes=True)
+
+    id: uuid.UUID
+    name: str
+    public_key: str
+    created_at: datetime
+
+
+class SignPayloadRequest(BaseModel):
+    payload: str
+
+
+class SignatureResponse(BaseModel):
+    signature: str
+
+
+class VerifySignatureRequest(BaseModel):
+    payload: str
+    signature: str
+
+
+class VerifySignatureResponse(BaseModel):
+    valid: bool