feat: implement SSH key management

- Add backend API endpoints for SSH key CRUD (POST, GET, DELETE)
- Implement Ed25519 key generation with Fernet-encrypted private keys
- Add frontend SSH keys page with generate, list, and delete functionality
- Include copy-to-clipboard for public keys
- Add responsive CSS styles for key cards
- Register ssh_keys router in main.py
- Add basic auth tests for SSH key endpoints

Quality gates: ruff ✓, mypy ✓, typecheck ✓, lint ✓

apps/web/src/api/ssh_keys.ts

@@ -0,0 +1,26 @@
+import { apiClient } from "./client";
+
+export interface SSHKey {
+  id: string;
+  name: string;
+  public_key: string;
+  created_at: string;
+}
+
+export interface SSHKeyCreate {
+  name: string;
+}
+
+export async function listSSHKeys(): Promise<SSHKey[]> {
+  const response = await apiClient.get<SSHKey[]>("/ssh-keys");
+  return response.data;
+}
+
+export async function createSSHKey(data: SSHKeyCreate): Promise<SSHKey> {
+  const response = await apiClient.post<SSHKey>("/ssh-keys", data);
+  return response.data;
+}
+
+export async function deleteSSHKey(keyId: string): Promise<void> {
+  await apiClient.delete(`/ssh-keys/${keyId}`);
+}